A silicone vaginal ring releasing 5-10 mug oestradiol/24 h for a minimum of 90 days has been developed for treatment of urogenital mucosal atrophy. The efficacy, safety and acceptability of the oestradiol-releasing ring were studied in 222 postmenopausal women with symptoms and signs of atrophic vaginal mucosa. The maturation of the vaginal epithelium, as measured by cytological parameters, was significantly improved during treatment. No proliferation of the endometrium was encountered. The therapy had a significant effect on symptoms (vaginal dryness, pruritus vulvae, dyspareunia, urinary urgency) and on signs of atrophic vaginitis, with cure/improvement registered in greater-than-or-equal-to 90%. The patient acceptability was high, since greater-than-or-equal-to 90% did not report any discomfort with the ring. Almost all of the sexually active women had the ring in place during coitus and in less-than-or-equal-to 2% of cases discomfort was noticed by them or the partner. It is concluded that a vaginal silicone ring giving a continuous release of an ultra-low dose of oestradiol is an effective and safe treatment for urogenital oestrogen deficiency. No addition of progestagen is needed.