In the present study we aimed to define the prevalence of polycystic ovaries (PCO), using the revised ultrasound criterion, in Chinese women with previous gestational diabetes mellitus (GDM), as well as their associated clinical, hormonal and biochemical characteristics. Seventy Chinese women with previous GDM were recruited as the study group. The control group comprised women matched for age, parity and delivery year who had a normal oral glucose tolerance test during their index pregnancy. Two- and three-dimensional ultrasound scans were performed to study ovarian morphology and ovarian stromal blood flow. Anthropometric, hormonal and biochemical profiles were compared between women with and without ultrasound features of PCO. The prevalence of PCO in Chinese women was 23%. The group with a history of GDM had a higher but not statistically significant prevalence of PCO (34%). Compared with controls, they had significantly higher incidence of obesity, impaired glucose tolerance or diabetes, fasting insulin and leptin levels, and their lipid profile was less favorable. Also, their level of sex hormone-binding globulin was significantly lower and hence their free androgen index was higher, and so was their level of dehydroepiandrosterone sulfate. There was a trend for the study group to have higher ovarian stromal blood flow.