The effects of nonalcoholic liver disease on sexual desire, arousal, activity, orgasmic function and satisfaction and serum testosterone levels were studied in 75 men with nonalcoholic liver disease. Each man was interviewed about his sexual behavior and problems and was asked to comment on whether he felt liver disease affected his sexual function. The average age of the patients was 49 yr, and a wide variety of liver diseases was represented. Child-Pugh grading was A in 51 patients, B in 18 and C in 6; the mean duration of liver disease was 8 yr. Sexual desire, arousal and activity of patients with grade A disease were within the ranges observed in studies of healthy men of comparable age. Diminished sexual desire was reported by 2% of grade A patients and 35% of grade B and C patients (p less than 0.005). Arousal problems were noted by 16% of grade A patients, 60% of grade B patients and 67% of C patients (p less than 0.005). Loss of erection and inability to regain erection were noted by 7%, 40% and 67% of grade A, B and C patients, respectively (p less than 0.01). Premature and retarded ejaculation were more frequent in patients classed in Child-Pugh grades B and C. Frequency of coitus and orgasm were significantly higher in grade A patients than in grade B and C patients. Total and free testosterone levels were (in nanograms per milliliter) A, 677/1.78; B, 416/1.06; and C, 178/0.43 (p less than 0.002). We concluded that Child-Pugh grade A nonalcoholic liver disease in men does not affect sexual desire, function or performance. Men with disease grades B and C have significant sexual dysfunction and significant reduction of both total and free testosterone levels.