We identified characteristics of devices that caused needle-stick injuries in a university hospital over a 10-month period. Hospital employees who reported needle sticks were interviewed about the types of devices causing injury and the circumstances of the injuries. Of 326 injuries studied, disposable syringes accounted for 35 percent, intravenous tubing and needle assemblies for 26 percent, prefilled cartridge syringes for 12 percent, winged steel-needle intravenous sets for 7 percent, phlebotomy needles for 5 percent, intravenous catheter stylets for 2 percent, and other devices for 13 percent. When the data were corrected for the number of each type of device purchased, disposable syringes had the lowest rate of needle sticks (6.9 per 100,000 syringes purchased). Devices that required disassembly had rates of injury of up to 5.3 times the rate for disposable syringes. One third of the injuries were related to recapping. Competing hazards were often cited as reasons for recapping. They included the risk of disassembling a device with an uncapped, contaminated needle and the difficulty of safely carrying several uncapped items to a disposal box in a single trip. New designs could provide safer methods for covering contaminated needles. Devices should be designed so that the worker's hands remain behind the needle as it is covered, the needle should be covered before disassembly of the device, and the needle should remain covered after disposal. Such improvements could reduce the incentives for recapping needles and lower the risk of needle-stick injuries among health care workers.