Nearly 6 years have passed since the Needlestick Safety and Prevention Act of 2000 was signed into law. We reviewed studies published since 1995 that evaluated the effect of safety-engineered device implementation on rates of percutaneous injury (PI) among health care workers. Criteria for inclusion of studies in the review were as follows: the intervention used to reduce PIs was a needleless system or a device with engineered sharps-injury protection, the outcome measurements included a PI rate, the intervention was evaluated in a defined population with clear comparison groups in clinical settings, and outcomes and denominators used for rate calculations were objectively measured using consistent methodology. All 17 studies reported substantial decreases in device-associated or overall PI rates after device implementation (range of reduction, 22%-100%). The majority of studies (n = 12) were uncontrolled before-after trials with limited ability to control for confounding variables. In addition, implementation of safety-engineered devices was often accompanied by other interventions, and direct measurement of outcomes was not performed. Nevertheless, safety-engineered devices are an important component in PI prevention.