Accidental needle sticks sustained by hospital personnel account for many hospital-related injuries, but little information is available dealing with risk factors amenable to control. We reviewed 316 reported needle stick injuries--accounting for one third of all work-related accidents--occurring in employees of our hospital over a 47-month period from 1975 to 1979. Housekeeping (127.0 cases per thousand employees annually) and laboratory personnel (104.7 per thousand) experienced the highest incidence of needle-stick injuries, followed by registered nurses (92.6 per thousand), but 60 percent of all injuries occurred in nursing personnel. Physicians rarely reported needle-stick injuries. Most injuries occurred during disposal of used needles (23.7 percent of all injuries), during the administration of parenteral injections or infusion therapy (21.2 percent), drawing blood (16.5 percent), recapping needles after use (12.0 percent), or handling linens or trash containing uncapped needles (16.1 percent). Sixty percent of the personnel who reported a needle puncture injury sought emergency room treatment where management was variable. The total cost of needle puncture injuries in our hospital over a 27-month period of $6,331. We recommend not recapping used needles and making widely available and promoting use of an efficient needle disposal system. All hospital personnel, including physicians, are urged to report needle-stick injuries to the hospital's Employee Health Service where evaluation and management can be effected most consistently by established protocols.