The purpose of our study was to examine the dependence of innate antiviral immunity on age and sex in human leukocytes. Innate antiviral immunity was measured by using the direct method of infection of leukocytes with vesicular stomatitis virus (VSV), which was selected as the indicatory virus for detection of immunity. The lack of VSV replication by infected leukocytes (0-1 log TCID50) was taken as an indicator for complete immunity; a low level of VSV replication (2-3 log) for partial immunity; and a high VSV titer (4 or more log) for the no or very low immunity. The kinetics of VSV replication was studied in leukocytes isolated from 127 individuals ranging in a age from 0 to 89 years. Individual differentiation in the kinetics of VSV replication indicated differing degrees of innate immunity even in newborns. Age-related differences in natural immunity were observed: low immunity in newborns, highest in the age group 31-40, and reduced in the age group >60. Sex dependent innate immunity was shown in the group of aged persons, as innate immunity was higher in women than in men. Innate immunity of leukocytes develops to age 30-40, after which immunity is gradually reduced. Sex dependence was observed only in the group of elderly persons, where women expressed higher immunity; this is probably a reason for their statistically greater longevity.