Objective: The risk of transmitting hepatitis C (HCV) by transfusion of anti-HCV-negative screened blood was estimated for the blood donor population of Baden-Württemberg (southwestern Germany). Methods: The data from the blood donors screened for anti-HCV and for HBsAg during 1990-1995 were analyzed. Results: The prevalence of confirmed anti-HCV-positive blood donations decreased continuously during the last 5 years, reaching 121 per 100,000 blood donations. A higher anti-HCV prevalence rate was found in female than in male blood donors (p<0.05). The estimated risk of transmitting HCV during the window period is 1:200,000 (1:97,000–1:1,400,000) for repeat donors. In 1995, the calculated risk for first-time donors was 1:20,000 (1:15,000–28,000). The incidence for HCV was 1.2 per 100,000 blood donations. Conclusion: The risk of transmitting hepatitis C by blood transfusion is low. Additional tests to shorten the window period to detect antibodies to HCV might increase the safety of blood transfusion.