The prevalence of hepatitis C virus (HCV) markers was investigated among health care staff with a high rate of exposure to blood or needle-stick injuries. After screening sera in pools of 10 at a time and individual testing of all reactive pools, totally 6 of 880 (0.7%; 95% confidence interval, 0.25-14.8%) were positive for anti-HCV, a figure of the same order as that found among Swedish first-time blood donors. Among the seropositives, all of five evaluable had been exposed to blood and four of five to needle-stick injuries. Our data suggest that HCV, in addition to hepatitis B virus, may constitute an occupational hazard for health care workers in Stockholm, even though the risk appears to be low, and personal risk factors such as intravenous drug abuse or blood transfusion could not be ruled out as sources of the infection.