Proteins in 68 vaginal secretions from 50 women were analyzed by SDS-polyacrylamide gel electrophoresis (SDS-PAGE). Although there were considerable numbers of intermediate types, the secretions could be classified into the following groups based on the densitometric patterns. A relatively low concentration of 67K protein (albumin) and a high concentration of 52K protein (IgG) were the patterns common to pre- and post-menstrual phases and pregnant stadium. A relatively high concentration of the 67K protein and a moderate concentration of the 52K protein characterized the midcycle. A considerably high concentration of 67K protein compared with the 79K (transferrin), 58K (IgA) and 52K bands was the pattern for menstrual phase and postpartum stage.