Objective: To evaluate androgen levels before and during IVF. To assess for an association between androgen levels and IVF stimulation parameters or IVF pregnancy outcome. Design: Prospective cohort study. Setting: Residency-based IVF program. Patient(s): One hundred seventeen infertility patients. Intervention(s): Androgen levels were evaluated on basal day 3 and during the IVF stimulation cycle. Main Outcome Measure(s): Pregnancy outcome rates and IVF stimulation parameters. Result(s): Mean serum androgen levels did not differ among different pregnancy outcomes. Multiple linear regression analysis revealed that body mass index (BMI) and oocyte number had a significant positive association with basal testosterone levels. Mean ovarian volume correlated negatively and follicle number correlated positively with testosterone levels on day 6 of stimulation. Peak E2 and BMI correlated positively with testosterone on day of hCG administration. The interval change in androgen levels throughout the IVF cycle was not associated with outcome rates. Likewise, threshold analysis did not reveal any significant androgen level that affected pregnancy outcome. Conclusion(s): Serum androgen levels during IVF correlate with IVF stimulation parameters. However, these data do not support an influence of serum androgen levels on IVF pregnancy outcome rates. Objective: To evaluate for an association between androgen levels and IVF stimulation parameters or IVF pregnancy outcome. Design: Prospective cohort study. Setting: Residency-based IVF program. Patient (s): One hundred seventeen Intervention (s): Androgenous levels were evaluated on basal day 3 and during the IVF stimulation cycle. Main Outcome Measure (s): Pregnancy outcome rates and IVF stimulation parameters. Result (s): Mean serum androgen levels did not differ Among different pregnancy outcomes. Multiple linear regression analysis revealed that body mass index (BMI) and oocyte number had a significant positive association with basal testosterone levels. Mean ovarian volume correlated negatively and follicle number positively positively correlated with testosterone levels on day 6 of stimulation. Peak E2 and BMI correlated positively with testosterone on day of hCG administration. The interval change in androgen levels throughou Th the IVF cycle was not associated with the outcome rates. However, these data do not support any significant androgen level that affected pregnancy outcome. Conclusion (s): Serum androgen levels during IVF correlate with IVF stimulation parameters. However, these data do not support an influence of serum androgen levels on IVF pregnancy outcome rates.