The endocrine effects of aminoglutethimide 125 mg twice daily and hydrocortisone 20 mg twice daily were assessed in 45 postmenopausal women with advanced breast cancer. Oestrone and oestradiol levels were suppressed by 60% within 2 weeks and suppression was maintained for more than 6 months of chronic treatment. In contrast to conventional dose AG with hydrocortisone, or low dose AG without hydrocortisone, delta 4 androstenedione was suppressed by 65%. This effect may contribute to optimal oestrogen suppression.