Injection pens are used by patients when auto-administering medication (insulin, interferon, apokinon etc.) by the subcutaneous route. The objective of this study was to evaluate the rate of injection pen use by healthcare workers (HCWs) and the associated risk of needlestick injuries to document and compare injury rates between injection pens and subcutaneous syringes. A one-year retrospective study was conducted in 24 sentinel French public hospitals. All needlestick injuries linked to subcutaneous injection procedures, which were voluntarily reported to occupational medicine departments by HCWs between October 1999 and September 2000, were documented using a standardized questionnaire. Additional data (total number of needlestick injuries reported, number of subcutaneous injection devices purchased) were collected over the same period. A total of 144 needlestick injuries associated with subcutaneous injection were reported. The needlestick injury rate for injection pens was six times the rate for disposable syringes. Needlestick injuries with injection pens accounted for 39% of needlestick injuries linked with subcutaneous injection. In all, 60% of needlestick injuries with injection pens were related to disassembly. Injection pens are associated with needlestick injuries six times more often than syringes. Nevertheless, injection pens have been shown to improve the quality of treatment for patients and may improve treatment observance. This study points to the need for safety-engineered injection pens.