To the Editor.— I wish to bring to the attention of your readership a much neglected study done in 1979 by Goodwin et al. 1 The authors chromatographed the volatile components of the vaginal secretions of female beagle dogs in an effort to identify specific pheromones. During estrus, when sexual receptivity was maximal, unique chromatographic peaks were noted. Concentration and analysis of these peaks revealed that methyl p -hydroxybenzoate was the main volatile component present. It was not present during proestrus or anestrus. The authors then applied pure methyl p -hydroxybenzoate to the vulva and in the vagina of anestrus females, and they sexually aroused and were mounted by males as though they were in estrus. Methyl p -hydroxybenzoate is, of course, better known to dermatologists as methylparaben, the common preservative in cosmetics and topical medications. Rover may not be oversexed at all. We may be inadvertently stimulating him with