An epidemic of Ross River virus (RRV) infection occurred in the Cook Islands in early 1980, and infected about 70% of the adult population of Rarotonga, the most populous island of the group. In July 1981, 80 mothers were identified as having been in the first trimester of pregnancy during the outbreak. Fifty-two of the at-risk mothers along with 63 of the offspring were ultimately examined. Of these 52 mothers, 39 (75%) were found to have serological evidence of RRV infection. Of the 63 infants located, 52 were examined serologically. None of the infants examined had serological evidence of RRV infection. There was no difference in age, size, or malformation rate in the offspring of the serologically positive or serologically negative mothers. These studies do not support an earlier report that RRV causes intrauterine infection.