Insulin resistance is a common characteristic of women with polycystic ovary syndrome (PCOS) who are known to differ in their in-vitro fertilization outcomes compared to non-PCOS patients. As insulin resistance can be found in a considerable proportion of normal individuals, we assessed its contribution to ovarian responsiveness and fertilization rate. 26 non-PCOS patients undergoing IVF for the first time were investigated. Insulin resistance was evaluated by using a euglycemic hyperinsulinemic clamp technique. According to multiple regression analysis insulin sensitivity, expressed as insulin stimulated glucose disposal rate, during euglycemic clamp (r = -0.81, p < 0.05 and r = -0.89; p < 0.01) and basal estradiol level (r = -0.54; p < 0.05 and r = -0.56; p < 0.05) appeared significant negative predictors of the number of fertilized oocytes and embryos, respectively. Furthermore, basal glucose level appeared independently as a significant positive predictor of the number of fertilized oocytes and the number of embryos. (r = 0.90; p < 0.01 and r = 0.96; p < 0.01 respectively). We conclude that blood glucose concentration and insulin resistance respectively are independent predictors of IVF outcome.