Polycystic ovary syndrome (PCOS) is characterized by chronic unovulation, hyperandrogenism, and insulin resistance. We evaluated factors that affect "nondipper" status during 24-hour ambulatory blood pressure monitoring (ABPM) and carotid intima-media thickness (cIMT) in PCOS. Forty-two nonobese women newly diagnosed as PCOS and 32 healthy women were included. After biochemical and hormonal measurements, the ovaries were imaged by pelvic ultrasonography and cIMT was measured by B-mode ultrasonography. A 24-hour ABPM was performed thereafter. Carotid IMT and the ratio of nondippers were elevated compared with controls. Homeostasis model assessment insulin resistance index (HOMA-IR) and low-density lipoprotein cholesterol (LDL-C) were found to be related with being a nondipper in PCOS. None of the parameters evaluated were found to correlate with cIMT. In conclusion, patients with PCOS had increased nondipping ratios and cIMT when compared with controls. Insulin resistance and LDL cholesterol are factors that are related to diurnal variation in normotensive and young patients with PCOS.