The objectives of this paper were to identify the types of sexual partners and condom use of migrant workers. Data for the study were drawn from a survey of 3,426 migrant workers in southern coastal and northern areas of Thailand conducted in 2004. Among sexually active men, 25% reported visiting a sex worker, 57% reported a regular partner, and 6% reported another non-regular partner in the last year. Reported condom use was high with sex workers (79% reported always use), but low with regular partners (4% ever use). Factors related to visiting sex workers included marital status (more visits if not married), longer residence in Thailand, occupation of seafarer or seafood production worker, Cambodian origin, and perceived AIDS risk. Condom use with sex workers was higher for younger men, married men, men who had been in Thailand longer, men with lower perceived AIDS risk, and men who drank alcohol less frequently.