The aromatase enzyme is responsible for conversion of androgens to phenolic estrogens. The five-dimensional quantitative structure-activity relationships (5D-QSAR) of a series of androstenedione analogs developed as aromatase inhibitors were studied using the Raptor program. The best model (N=47, q2=0.660, R2=0.719) showed contributions of the hydrophobic, hydrogen-bond-donating and hydrogen-bond-accepting fields to the activity. The model was also externally validated using 12 compounds (test set) not included in the model generation process. The statistical parameters from the model indicate that the data are well fitted and have good predictive ability. Thus it was possible to generate and to validate aromatase receptor surrogates through the prediction of relative free energies of aromatase inhibitors binding in receptor- modeling studies.