Conclusion 1. Four protein fractions were observed in 4 normal and one pathological semen specimens subjected to electrophoretic analysis. 2. The electrophoretic mobilities of these protein fractions after dialysis are identical with those of the albumin, alpha, beta, and gamma globulins of normal serum. 3. Average values for these components as percentages of the total nondialyzable semen protein are: beta globulin, 39.6; alpha globulin, 21.3; albumin, 19.9; and gamma globulin, 19.1. 4. The protein composition of the one pathological semen studied did not differ from the 4 normal semens.