The prevalence and risk factors of hepatitis B infection were studied in 354 non-drug abusing female prostitutes and 360 female controls in Tijuana, Mexico. Hepatitis B surface antigen (HBsAg) was found in the same percentage (0.8%) of prostitutes and controls. In contrast, antibody markers (anti-HBs or anti-HBc) were found in a significantly higher percentage of prostitutes than controls (8.2% vs. 2.2%, p = 0.0006). Prostitutes also had a higher prevalence of a positive RPR/FTA-ABS test for syphilis (p less than 0.0001). There was a significant association between the presence of hepatitis B markers and positive syphilis serology and a history of having had a STD. In this non-drug abusing population, prostitution was found to be a risk factor for total hepatitis B infection but not for surface antigenemia. Further studies are indicated to determine the incidence of chronic infection in adult women following sexual transmission of hepatitis B.