To assess the prevalence of hepatitis B virus (HBV) infection and immunity to measles, mumps, and rubella among refugees from the former Soviet Union (FSU). Descriptive study. Soviet Immigrant Health Care Program, Sinai Samaritan Hospital, Milwaukee, Wis. Consecutive sample of 496 Jewish refugees from the FSU presenting for new arrival screening from December 1, 1990, through January 11, 1993. Hepatitis B surface antigen (HBsAg), hepatitis B core antibody, hepatitis B surface antibody, and measles, mumps, and rubella antibodies. At least one hepatitis B marker was detected in 22% of the refugees, and HBsAg was detected in 0.4%. The rate of HBV infection (any marker present) increased with increasing age, ranging from 4% among those aged 0 through 19 years to 31% among those aged 50 through 59 years (chi 2 test for trend, 13.5; P < .001). Among those aged 0 through 19 years, 19% lacked antibody to measles, 8% lacked antibody to mumps, and 13% lacked antibody to rubella. Refugees who were less than 30 years of age were more than twice as likely to lack antibodies to measles, mumps, or rubella compared with those who were 30 years of age or older (relative risk, 2.8; 95% confidence interval, 1.8 to 4.2; P < .001). In our sample of Jewish refugees from the FSU (primarily Ukraine, Russia, and Belorussia), the rate of HBsAg positivity was low, suggesting that routine screening for HBV infection is not needed. Seronegativity to measles, mumps, and rubella was relatively common among those less than 30 years old. Those refugees who were born after 1957 should be given combined measles, mumps, and rubella vaccine unless their written documentation indicates previous receipt of these antigens according to the immunization schedule recommended in the United States.