Erectile dysfunction (ED) is a well recognised complication of bone marrow transplantation, which affects quality of life in adult patients. Although the major contributory factors include hypogonadism and psychogenic factors, the best treatment still remains to be established due to the complex aetiopathology of the condition. Here, we report our preliminary results in eight patients treated with testosterone replacement therapy and sildenafil. We studied eight male recipients of BMT aged 22-58 years, presenting with clinical features of hypogonadism, ED, diminished libido and ejaculatory disorders. ED was assessed clinically and by colour flow Doppler studies of the cavernosal vessels. Testicular function was assessed by testicular volume, FSH, LH and testosterone (T) measurements. Erectile performance, libido and ejaculatory function were determined by a structured interview. Patients had severe primary hypogonadism as evidenced by low mean testicular volume, elevated gonadotrophins and low normal mean testosterone levels compared with controls. All had Leydig cell insufficiency (LCI) with or without frank serum testosterone insufficiency. All except one had cavernosal arterial insufficiency. All patients received intramuscular injections of testosterone cypionate (250 mg 4 weekly) for 6 months and 50-100 mg of sildenafil orally, one to two times per week. All patients responded favourably as substantiated from the NIH consensus criteria. Our preliminary results suggest that this combined therapy is a safe and effective therapeutic approach in recipients of high-dose therapy presenting with ED after transplant.