Seminal fructose and sexual behavior were studied in intact and castrated, testosterone treated rabbits. Both seminal fructose and the intensity of sexual behavior increased after testosterone treatment. The dose-response relations were quite different for the two variables. A dose of 7.5 mg testosterone propionate injected every third day during the experiment restored the sexual behavior to precastrational levels, whereas a dose of 30 mg TP was insufficient to give seminal fructose concentrations comparable to those in the intact animals. There were no correlations between sexual behavior and seminal fructose in individual animals. Neither were any such correlations found in the intact animals. The data seem to support the idea of different hormonal mechanisms controlling sexual behavior and activity in the accessory sexual glands.