Polymyositis (PM) affects female gender during reproductive age; however, there is no study assessing ovarian reserve in these patients to evaluate ovarian reserve markers in PM. Eight female patients with PM (Bohan and Peter criteria, 1975) with aged 18-40 years, followed at our tertiary centre from March 2011 to May 2014, were invited to participate. They were age-matched with 16 healthy individuals (control group). All were evaluated at early follicular phase of menstrual cycle. Follicle stimulating hormone (FSH), estradiol, inhibin B, anti-Müllerian hormone (AMH) serum levels (ELISA) and sonographic antral follicle count (AFC) were determined. PM patients and controls had comparable mean age (31.4 ± 6.5 vs. 30.7 ± 6.2 years, P = 0.946), ethnicity and socioeconomic class (P > 0.05). PM mean age of onset was 27.3 ± 6.5 years and disease duration of 6.5 ± 4.1 years. Menstrual cycles were alike in both groups with a similar frequency of age at menarche, gynaecological age, duration and length of menstrual cycle (P > 0.05). The median serum level of AMH was significantly lower in PM compared to controls [0.7(0.3-3.4) vs. 3.1(1.4-4.0), P = 0.021]. AMH levels ≤1 ng/mL (50 vs. 6.3 %, P = 0.024) and very low AFC (37.5 vs. 6.3 %, P = 0.037) were significantly in PM patients versus controls. The other hormones (FSH, inhibin B and estradiol levels) were similar between both groups (P > 0.05). The present study was the first to identify subclinical ovarian dysfunction in PM patients during reproductive ages. Further study is necessary to assess the possible role of PM-related factors that may influence the ovarian function of these patients.