The effect of delta-9-tetrahydrocannabinol (THC) on rat Sertoli cell function was investigated. THC significantly increased ABP secretion by 1.5- to 2.1-fold but did not consistently enhance the stimulation of ABP induced by FSH, testosterone or dibutyryl cyclic AMP. ABP was measured by steady-state polyacrylamide gel electrophoresis, DEAE Bio-Gel and immunoassay; all three methods gave similar results. The minimal concentration of THC that stimulated ABP was 10 ng/ml; maximal stimulation was observed with 100-200 ng/ml. This effect was specific since THC did not affect gamma glutamyl transpeptidase activity or the secretion of plasminogen activator, lactate and transferrin. This observation that THC affects ABP secretion specifically is the first report of any differential effect of a drug on Sertoli cell secretion.