Objective: To evaluate whether differences in follicular fluid vascular endothelial growth factor (FF VEGF) concentrations are observed between women achieving a clinical pregnancy and those failing to conceive. Design: Retrospective chart review and analysis of FF VEGF concentrations. Setting: University teaching center. Patient(s): Fifty-seven women less than or equal to 42 years of age undergoing follicular aspiration in preparation for IVF or GIFT. Intervention(s): Analysis of FF VEGF concentrations and chart review of a single IVF or GIFT cycle. Main Outcome Measure(s): Follicular fluid VEGF concentrations, clinical pregnancy rate, age, ampules of gonadotropins used. oocytes retrieved, peak estradiol serum concentrations, day 3 FSH levels, and fertilization rate. Result(s): Women who did not conceive had higher FF VEGF concentrations than women achieving a clinical pregnancy (4,409 + 2,387 versus 2,793 + 1,180 pg/mL: P < .001). A negative correlation was observed between FF VEGF concentrations and peak estradiol levels and number of oocytes retrieved. A positive correlation was found for FP VEGF and patient's age and ampules of gonadotropins used. Conclusion(s): Elevated FF VEGF concentrations are associated with poor conception rates after IVF or GIFT. (Fertil Steril(R) 1998;70:836-9. (C) 1998 by American Society for Reproductive Medicine.).