Occupational injury data from the National Electronic Injury Surveillance System is reviewed. Reports from hospital records reveal that a large proportion of injuries are relatively minor. In 97 percent of cases, patients are treated and released; 24.4 percent involve only the fingers; and 47.8 percent are diagnosed as laceration, contusion, or abrasion. Estimates are misleading because emergency room cases constitute 36 percent of all injuries on the job or at place of business. Many minor injuries are treated at workplace medical facilities. The national system reports those that are serious enough to merit a trip to the hospital. Age, sex, and month specific incidence rates are available for the United States. In the summer, young male workers present more than 5 times the risk of other workers who are 55 years of age and older. Risks for female workers are an average of 25 percent that of males and do not display the pronounced seasonal trend of males. In 1977, NIOSH developed a program designed to provide previously unavailable details on job accidents. The Work Injury Report Survey consists of questionnaires that are mailed to injured workers who have filed worker's compensation claims. Questionnaires provide details on the characteristics of injured workers, exposure to various conditions, experience, training, personal protective equipment, and actions taken by employer after the accident. Occupational injury surveillance often proceeds from case series data that usually represents only frequency, and occasionally severity, of injury. The objectives of safety are to define problems, causal factors, and hypotheses clearly. Extensive use of surveillance data to identify and characterize risk factors will promote more effective research on workplace injury reduction.