In Thailand and elsewhere, some older persons remain sexually active well into late middle and old age. Sexually active older Thai men without a regular sexual partner may be at risk for contracting HIV. Since many of these older men came of age during an era when unprotected commercial sexual relations was normative for unmarried men, they may revert to these former practices, especially since older men have not been a target of intervention campaigns in Thailand. We explore these hypotheses using qualitative data from semi-structured, in-depth interviews of unmarried older Thai men, most of whom were in their 50's. Opportunities exist for several of the men we interviewed to engage in a fairly wide range of sexual relationships. Some do, but others choose celibacy because of declining interest; a wish to avoid financial hardships thought to be inextricably linked with sexual relationships; a wish to avoid social sanctions; and/or desires to pursue interests thought to be more appropriate for their age group. Risks for acquiring and spreading HIV do not appear to be great but such risks cannot be ruled out given how little we know about the sexual behavior of unmarried men in this age group.