Purpose This study intended to understand the intention of using condoms as protection from sexually transmitted diseases during casual sex amongst heterosexual male conscripts. Method This study recruited 751 male conscripts in 2002 from a military camp in Taiwan. The secondary data analysis related to the casual sex and condom was used in this study. Results A total of 751 conscripts were recruited and 72% (n=541) had sexual experience. Among 541 participants who had sex experience, 27% representd that they always used condoms or used them often; 53% self-reported having sexual intercourse at least four times a month; more than half of them traded money for sex, and 45% had one night stand experience. The three main reasons for use or nonuse of condoms were the same for sexually experienced or unexperienced conscripts: avoiding diseases, avoiding pregnancy, and request of the partner. The results from multiple regression analysis indicated that past condom use, number of occasional partner, and experience of one night stand were significantly associated with intention of condom use with casual partners. Conclusion The findings of the study indicated that male conscripts had a substantial percentage of casual sex, and only a few used condoms with casual sex partners. The results can provide evidence for reasons of using or not using condoms while having sex and can be considered for designing condom use intervention program in increasing rates of condom use among men.