Abstract Although phallometric assessment is the best scientific method for measuring male sexual interest, it is intrusive and highly technical. We examined viewing time as an unobtrusive and technically simple measure of sexual preference and compared the discrimination obtained by viewing time measures with that obtained by phallometric measures. Slides of nude males and females of various ages were shown to child molesters and normal men while their viewing times were recorded. Subjects then rated the sexual attractiveness of the stimulus persons. Phallometric assessments using the same stimulus categories were also given to some of the Ss. Deviance scores calculated from the viewing time data significantly discriminated between the child molesters and the normals, although the discrimination achieved was less than that obtained using phallometric measures. Sexual attractiveness ratings did not differentiate the two groups. Among the normal men, viewing time and sexual attractiveness ratings were highly correlated; but the correlation was much lower for child molesters. Viewing time shows considerable promise as an unobtrusive measure of male sexual interest.