Our objective was to compare the relationship between age, basal follicle stimulating hormone (FSH) level and ultrasound-measured mean ovarian volume (MOV) and mean antral follicle counts (MFC) in a group of infertile and fertile women between the ages of 35 and 45 years. Menstrual cycle day 3 serum FSH, MOV and MFC were analyzed in 62 infertile and 53 fertile women. Basal FSH and MFC did not differ between infertile and fertile women, whereas MOV was significantly smaller in infertile women (p < 0.05). In the infertile group, there was a negative correlation between MO V and age (rho = -0.389, p < 0.05), between MOV and basal FSH (rho = -0.495, p < 0.01), and between MFC and age (rho = - 0.553, p < 0.01). In the fertile group, there was a strong negative correlation between MOV and basal FSH (rho = -0.631, p < 0.01), and between MFC and basal FSH (rho = -0.710, p < 0.01). Mean basal FSH, MOV and MFC did not differ between subgroups of patients with different causes of infertility. In the infertile group, patients with small ovaries Of volume less than 1.8 cm(3) (mean volume - 1 SD) had higher mean basal FSH (p < 0.05) and lower MFC (p < 0.01) levels than patients with normal ovarian volume. In conclusion, transvaginal ultrasound (TVU) indices and indirect hormonal parameters Of ovarian reserve were similar in infertile and fertile women aged between 35 and 45 years. It is suggested that, in infertile women above 35 years of age, TVU rather than hormonal parameters be preferred, based on our data showing a stronger association between age and TVU indices of ovarian reserve than between age and increase in basal FSH level. Thus, TVU assessment of ovarian volume and antral follicle counts is a practical and cost-effective, if not better, technique for ovarian reserve testing.