During the winters of 1974-1975 and 1975-1976, hibernating Culex pipiens pipiens L. were collected from a large population at Fort Mott in Salem County, New Jersey and examined for parous rates to determine the percentage which ingested blood prior to diapause. The information was used to help assess the likelihood of Cx. p. pipiens harboring arboviruses over the winter in New Jersey. Parity was determined by the Detinova method of ovarian tracheolation as well as the stage of ovarian development in individual ovarioles. Results for 1974-1975 showed that of 120 mosquitoes examined, 119 were nulliparous, with the single specimen taken early in the hibernating period. A further indication of nulliparity was obtained from the examination of individual ovarioles since all those examined were in stage N, the earliest stage in the developmental process. During 1975-1976, only 12 of 820 Cx. p. pipiens were parous, 6 of which found in October. No parous mosquitoes were found during February or March. Data suggest that some parous mosquitoes enter hibernation, but few, if any, survive the winter. Even with a low percentage of the population which might exhibit gonotrophic dissociation, Cx. p. pipiens seems to be an unlikely source for overwintering virus.