To evaluate the predictive value of basal serum anti-müllerian hormone level and small antral follicle count for high ovarian response to controlled ovarian hyperstimulation. A total of 159 patients were prospectively included. Basal serum anti-müllerian hormone and small antral follicle count (2-6 mm) were measured. Small antral follicle count and anti-müllerian hormone have similar predictive accuracy for high ovarian response with area under curve of 0.961 and 0.922, respectively. The sensitivity and specificity for prediction of high ovarian response were 89% and 92% for small antral follicle count and 93% and 78% for anti-müllerian hormone at the cutoff values of > or = 16 and > or = 34.5 pmol/l, respectively. Small antral follicle count and anti-müllerian hormone are equally accurate predictors of high ovarian response and facilitate determination of the optimal strategy for controlled ovarian hyperstimulation.