In women with polycystic ovary syndrome (PCOS) weight loss is associated with an improvement in insulin sensitivity and a reduction of the insulin concentration in the plasma. It is clear, then, that the first therapeutic approach that can be considered in obese PCOS patients for restoration of the menstrual cycle should be a diet. The aim of our study was to examine the effect of long-term caloric restriction on the clinical and biochemical abnormalities in obese PCOS women. The results obtained make it clear that caloric restriction for 4 weeks causes an increase in SHBG and decreases of free testosterone and insulin, with consequent improvement of the clinical picture.