BACKGROUND: Frequent endocrine disorders have been reported after allogeneic stem-cell transplant, but data on adult survivors of autologous transplants are still scarce. METHODS: In this prospective study we investigated early (at 3 months) and late (at 12 months) endocrine dysfunctions in 95 consecutive autologous stem-cell transplant recipients (47 men and 48 women) aged 16 to 55 years. The functions of the hypothalamic-pituitary-gonadal/thyroid/adrenal/somatotroph axis were evaluated. RESULTS: Three months after the transplant, insulin-like growth factor-1 values were below the normal range in 53 patients (56%); 37 of 40 women (93%) of reproductive age experienced precocious ovarian failure; 39 of 46 men (85%) showed high follicular stimulating hormone, and 17 men (37%) showed low testosterone levels. Adrenal insufficiency occurred in 28 patients (30%) during the peritransplant period after corticosteroid withdrawal. Transient subclinical hyperthyroidism was found in 15 patients (16%). Transient "low T-3" syndrome was revealed in 29 patients (31%). Twelve months after the transplant, insulin-like growth factor-1 values were still low in 36 patients (38%). Menstrual cycles resumed in four women; follicular stimulating hormone, luteinizing hormone, and estradiol levels improved in 10 patients. Testosterone was low in only two men (4%). Seminal analysis revealed azoospermia in 32 (91%) of 35 men examined. Subclinical hypothyroidism was found in 11 patients (12%); eight of them had previously received radiotherapy for the upper half of the body.