Immigrant children who enter the United States without immunization records may be required to receive vaccines for diseases to which they are already immune or for which they have previously received immunization. We tested 669 newly arrived refugees (age range, 0-20 years) for antibody to measles, rubella, and varicella, to determine the seroprevalence of antibodies to these diseases in this group of immigrants. Five hundred forty-nine (82%) of 669 patients had antibody to measles, 545 (82%) of 668 had antibody to rubella, and 430 (64%) of 668 had antibody to varicella. Antibody to all 3 diseases increased with increasing age. No clinically significant differences in presence of antibody were noted by region of origin.