Using a sample of 33 healthy young men, 6 blood samples were obtained in the course of 2 weeks, and testosterone, dihydrotestosterone, and estradiol levels determined. The amount of free testosterone in the saliva was also ascertained for 23 of the subjects. All participants kept a daily record of their sexual activity during the investigational period. An interindividual comparison revealed a significant positive correlation between serum testosterone levels and the frequency of orgasms as well as a significant negative correlation between estradiol concentrations and the frequency of sexual activity without orgasm. The comparison of hormone levels to sexual behavior, prior to and after the individual sampling, reveals significant positive correlations between the serum testosterone and the extent of the free testosterone on the one hand and both the preceding and subsequent frequency of orgasms on the other. The estradiol levels showed a significant negative correlation with both the preceding and the subsequent frequencies of sexual activity without orgasm.