We report a simple and direct procedure for the measurement of circulating free testosterone concentrations by using saliva as a matrix rather than serum. There is a close correlation between saliva testosterone values measured by radioimmunoassay, calculated values of free testosterone, and free testosterone estimated by equilibrium dialysis. Our method is direct and has the advantage that the biologic fluid can be obtained routinely by noninvasive techniques outside the clinic during a course of therapy. We also show that a single saliva value is of greater diagnostic use than any of the currently used androgen assays. Testosterone was found to be elevated in the saliva of 17 infertility patients diagnosed as having polycystic ovarian syndrome, 14 of these patients were hirsute.