Measles virus vaccine, live, attenuated (Schwarz strain), was administered in June 1965 to 84 Eskimo and 21 white children, 7 months to 6 years of age, living in a village of the Canadian Eastern Arctic. Specific antibodies to measles virus were detected in 100% of 42 serum specimens from the Eskimo children and 15 (94%) of 16 serum specimens from the white children. Except for high fever, severe clinical reactions were not observed during the vaccination program. Rectal temperatures over 103 F (39.4 C) were noted in 12 (33.3%) of 36 Eskimo children and in 3 (18.8%) of 16 white children 6 to 11 days following vaccination. Mild rash developed in 11 (30.6%) of 36 Eskimo and in 6 (37.5%) of 16 white children. These data have demonstrated the safety and efficacy of use of the Schwarz vaccine among Eskimo children.