We compared litter size (and its relationship with female SVL), minimum size of females at sexual maturity, and minimum adult size of females, among different populations [from eight coastal sea level and two midelevation (600–800 m) sites] of the live-bearing skink Mabuya agilis in the southeastern Brazilian states of Espírito Santo and Rio de Janeiro. There were no apparent differences in litter size among populations within either lowland or highland groups, but each group differed significantly from the other: highland females had larger litters (mean = 5.6, range 2–9) than those from lowland sites (mean = 3.3, range 1–6). There was a significant positive relationship between litter size and female SVL for each group, but the slope of the regression differed between lowland and highland females, with the latter tending to have larger litters for a given SVL. Highland females also reach larger body sizes, although their minimum size at sexual maturity and minimum adult size are just slightly greater than those from lowland populations. We interpret such intraspecific variation relative to possible effects of the physical environment and of genetic factors on reproduction.