The authors retrospectively evaluated 1,773 climacteric outpatients in order to establish: (a) criteria able to distinguish different conditions in the transitional phase before menopause (advanced fertile age and premenopause) and (b) premenopause-related changes during the transition from one to the other of several clinical and laboratory parameters. Results showed an increase in gonadotropin plasma levels, a decrease in estrogen plasma levels and a greater frequency of women complaining of hot flushes in premenopause compared to advanced fertile age, as an expression of the progressive decline of ovarian function. Premenopanse-related changes were a decrease in thyroid function and an increase in the body mass index, the beginning of bone loss, an increase in glucose, total cholesterol and triglyceride serum levels and a greater frequency of women complaining of hypertension and urinary stress incontinence. An increase in total proteins, uric acid and aminotransferase serum levels was also noted.