Objective: To evaluate the meiotic spindle and chromosome distribution of in vitro-matured oocytes from infertile nonobese or obese women with polycystic ovary syndrome (PCOS) and to compare in vitro maturation (IVM) rates between groups. Design: Prospective study. Setting: Hospital-based IVF center. Patients: A total of 99 patients (26 obese women with PCOS, 25 nonobese women with PCOS, and 48 controls) undergoing stimulated cycles for intracytoplasmic sperm injection had immature oocytes for IVM. Interventions: Immature oocytes (germinal vesicle and metaphase I stages) were collected from obese and nonobese PCOS patients and controlled infertile patients. The meiotic spindle and chromosome configurations in oocytes matured in vitro were studied by confocal microscopy, with fluorescent labeling techniques for visualization of both microtubules and chromosomes. Main Outcome Measures: Meiotic spindle and associated chromosome configurations. Results: There were no significant differences between the different types of PCOS and the control group with respect to IVM rates (61.8, 63.8, and 63.2%, respectively), the percentage of spindle abnormalities in metaphase II oocytes (40.6, 42.9, and 37.5%, respectively) or chromosome abnormalities in metaphase II oocytes (31.2, 34.3, and 33.3%, respectively). Conclusions: In vitro-matured oocytes obtained from stimulated cycles had a high ratio of meiotic abnormalities. The different types of PCOS had the same ratio of meiotic abnormalities.