Accurate reporting of work-related conditions is necessary to monitor workplace health and safety, and to identify the interventions that are most needed. Reporting systems may be designed primarily for external agencies (OSHA or workers' compensation) or for the employer's own use. Under-reporting of workplace injuries and illnesses is common due to a variety of causes and influences. Based on previous reports, the authors were especially interested in the role of safety incentive programmes on under-reporting. Safety incentive programmes typically reward supervisors and employees for reducing workplace injury rates, and thus may unintentionally inhibit proper reporting. The authors describe a case study of several industrial facilities in order to illustrate the extent of under-reporting and the reasons for its occurrence. A questionnaire and interview survey was administered to 110 workers performing similar tasks and several managers, health, and safety personnel at each of three industrial facilities. Although less than 5% of workers had officially reported a work-related injury or illness during the past year, over 85% experienced work-related symptoms, 50% had persistent work-related problems, and 30% reported either lost time from work or work restrictions because of their ailment. Workers described several reasons for not reporting their injuries, including fear of reprisal, a belief that pain was an ordinary consequence of work activity or ageing, lack of management responsiveness after prior reports, and a desire not to lose their usual job. Interviews with management representatives revealed administrative and other barriers to reporting, stemming from their desire to attain a goal of no reported injuries, and misconceptions about requirements for recordability. The corporate and facility safety incentives appeared to have an indirect, but significant negative influence on the proper reporting of workplace injuries by workers. A variety of influences may contribute to under-reporting; because of under-reporting, worker surveys and symptom reports may provide more valuable and timely information on risks than recordable injury logs. Safety incentive programmes should be carefully designed to ensure that they provide a stimulus for safety-related changes, and to discourage under-reporting. A case-control study of similar establishments, or data before and after instituting safety incentives, would be required to more clearly establish the role of these programmes in under-reporting.