['With the occasional reports of unexpectedly poor ovarian response to controlled ovarian hyperstimulation (COH) for IVF in young normally cyclic women in mind, we studied age-related ovarian response to COH in a group of women who underwent standard IVF.', "Ovarian response to COH was defined as the number of follicles > or = 14 mm on the day of hCG administration. Ovarian response to COH was analysed by multiple regression analysis with woman's age and basal FSH concentration as explanatory variables in a prospective cohort of patients with idiopathic and mild male factor subfertility (n = 85), and additionally in a large retrospective cohort of women with unexplained, mild male and tubal subfertility (n = 1155), with age as explanatory variable.", 'Ovarian response to COH was associated significantly with age (P < 0.001) and basal FSH concentration (P = 0.002). However, in women with idiopathic or mild male subfertility, in both cohorts the relationship took the form of an inverted U-shape with both older and--surprisingly--young women having a reduced ovarian response (P < 0.001). Maximum ovarian response was around the age of 28 years. In women with tubal infertility, there was only a linear decline of ovarian response with age.'] Is ovarian response to standard gonadotrophin stimulation for IVF decreased not only in older but also in younger women in couples with idiopathic and male subfertility?