Many patients with hyperandrogenemia are overweight or obese, which exacerbates morbidities associated with polycystic ovary syndrome (PCOS). To examine the ability of testosterone (T) to generate PCOS-like symptoms, monkeys received T or cholesterol (control) implants (n=6/group) beginning prepubertally. As previously reported, T-treated animals had increased neuroendocrine drive to the reproductive axis (increased LH pulse frequency) at 5 years, without remarkable changes in ovarian or metabolic features. To examine the combined effects of T and obesity, at 5.5 years (human equivalent age: 17 years), monkeys were placed on a high-calorie, high-fat diet typical of Western cultures (Western style diet; WSD), which increased body fat from <2% (pre-WSD) to 15-19% (14 months WSD). By 6 months on WSD, LH pulse frequency in the controls increased to that of T-treated animals, whereas LH pulse amplitude decreased in both groups and remained low. The numbers of antral follicles present during the early follicular phase increased in both groups on the WSD, but maximal follicular size decreased by 50%. During the late follicular phase, T-treated females had greater numbers of small antral follicles than controls. T-treated monkeys also had lower progesterone during the luteal phase of the menstrual cycle. Although fasting insulin did not vary between groups, T-treated animals had decreased insulin sensitivity after one year on WSD. Thus, while WSD consumption alone led to some features characteristic of PCOS, T+WSD caused a more severe phenotype with regards to insulin insensitivity, increased numbers of antral follicles at midcycle, and decreased circulating luteal phase progesterone levels.