diff --git a/rules-tests/DeadCode/Rector/ClassMethod/RemoveUselessReturnTagRector/Fixture/skip_conditional_return_bool.php.inc b/rules-tests/DeadCode/Rector/ClassMethod/RemoveUselessReturnTagRector/Fixture/skip_conditional_return_bool.php.inc
new file mode 100644
index 00000000000..d80499f921c
--- /dev/null
+++ b/rules-tests/DeadCode/Rector/ClassMethod/RemoveUselessReturnTagRector/Fixture/skip_conditional_return_bool.php.inc
@@ -0,0 +1,26 @@
+<?php
+
+namespace Rector\Tests\DeadCode\Rector\ClassMethod\RemoveUselessReturnTagRector\Fixture;
+
+final class SkipConditionalReturnBool
+{
+    /**
+     * @param array<mixed> $data
+     *
+     * @return ($data is list<array> ? true : false)
+     */
+    private function isListOfArrays(array $data): bool
+    {
+        return \array_is_list($data) && \array_all($data, static fn (mixed $item): bool => \is_array($item));
+    }
+
+    /**
+     * @template T of string|int
+     * @param T $value
+     * @return (T is string ? true : false)
+     */
+    public function isString(string|int $value): bool
+    {
+        return is_string($value);
+    }
+}
diff --git a/rules/DeadCode/PhpDoc/DeadReturnTagValueNodeAnalyzer.php b/rules/DeadCode/PhpDoc/DeadReturnTagValueNodeAnalyzer.php
index 393c078a92f..04fa30351b9 100644
--- a/rules/DeadCode/PhpDoc/DeadReturnTagValueNodeAnalyzer.php
+++ b/rules/DeadCode/PhpDoc/DeadReturnTagValueNodeAnalyzer.php
@@ -10,6 +10,8 @@
 use PhpParser\Node\Stmt\Function_;
 use PHPStan\Analyser\Scope;
 use PHPStan\PhpDocParser\Ast\PhpDoc\ReturnTagValueNode;
+use PHPStan\PhpDocParser\Ast\Type\ConditionalTypeForParameterNode;
+use PHPStan\PhpDocParser\Ast\Type\ConditionalTypeNode;
 use PHPStan\PhpDocParser\Ast\Type\GenericTypeNode;
 use PHPStan\PhpDocParser\Ast\Type\IdentifierTypeNode;
 use PHPStan\PhpDocParser\Ast\Type\ThisTypeNode;
@@ -54,6 +56,10 @@ public function isDead(ReturnTagValueNode $returnTagValueNode, ClassMethod|Funct
             return false;
         }
 
+        if ($returnTagValueNode->type instanceof ConditionalTypeNode || $returnTagValueNode->type instanceof ConditionalTypeForParameterNode) {
+            return false;
+        }
+
         $docType = $this->staticTypeMapper->mapPHPStanPhpDocTypeNodeToPHPStanType(
             $returnTagValueNode->type,
             $functionLike