diff --git a/solidity/external-call-return-value-not-checked.sol b/solidity/external-call-return-value-not-checked.sol
new file mode 100644
index 0000000..00aed84
--- /dev/null
+++ b/solidity/external-call-return-value-not-checked.sol
@@ -0,0 +1,98 @@
+pragma solidity ^0.8.17;
+
+contract Test {
+    function setVars(address payable _contract, uint _num) public payable {
+        
+        // ok: external-call-return-value-not-checked
+        (bool success, ) = _contract.delegatecall(
+            abi.encodeWithSignature("setVars(uint256)", _num)
+        );
+        require(success, "Error");
+        
+        // ok: external-call-return-value-not-checked
+        (bool success2, ) = _contract.staticcall(
+            abi.encodeWithSignature("setVars(uint256)", _num)
+        );
+        if (!success2) revert();
+
+        // // ok: external-call-return-value-not-checked
+        // (bool success3, bytes memory data) = _contract.staticcall(
+        //     abi.encodeWithSignature("setVars(uint256)", _num)
+        // );
+        // if (success3 != 0) revert();
+
+        // ok: external-call-return-value-not-checked
+        (bool success4, bytes memory data) = _contract.call(
+            abi.encodeWithSignature("setVars(uint256)", _num)
+        );
+        if (success4){
+            revert();
+        }
+        // // ok: external-call-return-value-not-checked
+        // bool success5 = _contract.send(_num);
+        // if (success5 == 0) revert();
+
+        // ok: external-call-return-value-not-checked
+        (bool success6, ) = _contract.delegatecall(
+            abi.encodeWithSignature("setVars(uint256)", _num)
+        );
+        require(success6 && 1 == 1, "Error");
+
+        // ok: external-call-return-value-not-checked
+        (bool success, bytes memory data) = address(token).call(abi.encodeWithSelector(IERC20.transfer.selector, to, value));
+        if (!(success && (data.length == 0 || abi.decode(data, (bool))))) revert(RevertMsgExtractor.getRevertMsg(data));
+
+        // ok: external-call-return-value-not-checked    
+        (bool sendBackSuccess, ) = payable(msg.sender).call{value: address(this).balance}('');
+        require(sendBackSuccess, 'Could not send remaining funds to the payer');
+    }
+
+    // function setVars2(address payable _contract, uint _num) public payable {
+    //     // ruleid: external-call-return-value-not-checked
+    //      _contract.call(abi.encodeWithSignature("setVars(uint256)", _num));
+    // }
+
+    function setVars3(address payable _contract, uint _num) public payable {
+        // ruleid: external-call-return-value-not-checked
+        (bool success1, bytes memory data) = _contract.call(
+            abi.encodeWithSignature("setVars(uint256)", _num)
+        );
+    }
+
+    // function setVars4(address payable _contract, uint _num) public payable {
+    //     // ruleid: external-call-return-value-not-checked
+    //     bool success2 = _contract.send(1 ether);
+
+    // }
+    
+    function setVars5() public payable{
+        // ok: external-call-return-value-not-checked 
+        (bool success1, bytes memory data) = _contract.call(
+            abi.encodeWithSignature("setVars(uint256)", _num)
+        );
+
+        return success1 && 1 == 1;
+    }
+    
+    function withdrawTaxBalance_() external nonReentrant onlyOwner {
+        (bool temp1, ) = payable(solidityDevWallet).call{
+            value: (taxBalance * solidityDevShare) / SHAREDIVISOR
+        }("");
+        (bool temp2, ) = payable(frontendDevWallet).call{
+            value: (taxBalance * frontendDevShare) / SHAREDIVISOR
+        }("");
+        (bool temp3, ) = payable(projectLeadWallet).call{
+            value: (taxBalance * projectLeadShare) / SHAREDIVISOR
+        }("");
+        (bool temp4, ) = payable(apeHarambeWallet).call{
+            value: (taxBalance * apeHarambeShare) / SHAREDIVISOR
+        }("");
+
+        // ok: external-call-return-value-not-checked 
+        (bool temp5, ) = payable(treasuryWallet).call{
+            value: (taxBalance * treasuryShare) / SHAREDIVISOR
+        }("");
+        assert(temp1 && temp2 && temp3 && temp4 && temp5);
+        taxBalance = 0;
+    }
+}
diff --git a/solidity/external-call-return-value-not-checked.yaml b/solidity/external-call-return-value-not-checked.yaml
new file mode 100644
index 0000000..8df6798
--- /dev/null
+++ b/solidity/external-call-return-value-not-checked.yaml
@@ -0,0 +1,66 @@
+rules:
+  - id: external-call-return-value-not-checked
+    message: Functions call, staticcall, delegatecall, send returns a boolean indicating whether the call completed successfully. Not testing explicitly whether these calls fail may lead to unexpected behavior in the caller contract.
+    languages:
+      - solidity
+    severity: WARNING
+    metadata:
+      references:
+        - https://entethalliance.org/specs/ethtrust-sl/v1/#req-1-check-return
+      tags:
+        - ethtrust
+        - external-call
+    patterns:
+      - pattern-either:
+          - pattern: (bool $SUCC, ) = $ADDR.$METHOD(...);
+          - pattern: (bool $SUCC, ) = $ADDR.$METHOD{value:$VAL}(...);
+          - pattern: (bool $SUCC, ) = $ADDR.$METHOD{gas:$GAS}(...);
+          - pattern: (bool $SUCC, ) = $ADDR.$METHOD{value:$VAL, gas:$GAS}(...);
+          - pattern: (bool $SUCC, ) = $ADDR.$METHOD{gas:$GAS, value:$VAL}(...);
+          - pattern: (bool $SUCC, bytes memory $DATA) = $ADDR.$METHOD(...);
+          - pattern: (bool $SUCC, bytes memory $DATA) = $ADDR.$METHOD{value:$VAL}(...);
+          - pattern: (bool $SUCC, bytes memory $DATA) = $ADDR.$METHOD{gas:$GAS}(...);
+          - pattern: (bool $SUCC, bytes memory $DATA) = $ADDR.$METHOD{value:$VAL,
+              gas:$GAS}(...);
+          - pattern: (bool $SUCC, bytes memory $DATA) = $ADDR.$METHOD{gas:$GAS,
+              value:$VAL}(...);
+          - pattern: $ADDR.$METHOD(...);
+          - pattern: $ADDR.$METHOD{value:$VAL}(...);
+          - pattern: $ADDR.$METHOD{gas:$GAS}(...);
+          - pattern: $ADDR.$METHOD{value:$VAL, gas:$GAS}(...);
+          - pattern: $ADDR.$METHOD{gas:$GAS, value:$VAL}(...);
+      - metavariable-regex:
+          metavariable: $METHOD
+          regex: ^(call|delegatecall|staticcall|send)$ 
+      - pattern-not-inside: |
+          function $FUNC(...){
+            ...
+            require(<... $SUCC ...>, ...);
+            ...
+          } 
+      - pattern-not-inside: |
+          function $FUNC(...){
+            ...
+            if (<... $SUCC ...>){
+              ...
+            }
+            ...
+          } 
+      - pattern-not-inside: |
+          function $FUNC(...){
+            ...
+            return <... $SUCC ...>;
+          } 
+      - pattern-not-inside: |
+          function $FUNC(...){
+            ...
+            $CHECK(..., $SUCC, ...);
+            ...
+          }   
+      - pattern-not-inside: |
+          function $FUNC(...){
+            ...
+            assert(<... $SUCC ...>);
+            ...
+          }  
+