Repeated weighings and measurements of the incubating eggs of Malaclemys centrata, Sceloporus undulatus and Caretta caretta show an increase in both weight and size. Desiccation indicates that the increased weight of M. centrata and C. caretta eggs can be attributed to water absorption. Similar studies were not made on S. undulatus eggs but it seems reasonable to suppose that the increase in weight is due to the same factor. Volume increase is less than weight increase which may account for a part of the increased turgidity.