This brief article discusses warning signs of fraudulent workers' compensation claims. These warning signs include claims that: (1) coincide with layoffs; (2) occur after weekends; (3) are filed well after the time of injury; (4) have an apparent seasonal pattern; (5) are inconsistent with the type of work performed by the employee; or (6) involve malingering. Tips on effective investigation of suspected fraudulent claims and a general list of documentation needed to support the investigation are provided. The security personnel/human resources link also is discussed.