A total of 978 Japanese students, who visited the health services center of a college in Japan for medical check-ups, were asked to anonymously complete a 55-item questionnaire which assessed their attitudes toward sex and sexual behavior. Seven hundred eighty-five Japanese students (80.3%) responded to the questionnaire. In this survey, 90% of male students and 83% of female students indicated that they expected to have sexual intercourse before marriage, while 8% of male students and 3% of female students indicated that it was not wrong to have extramarital sexual intercourse after marriage. In addition, 75% of sexually experienced students reported that they used a condom during their first sexual intercourse, while 73% reported using a condom during their most recent sexual intercourse. The more sexual partners students had had up to the time of the study, the less condom use they reported for both their first and most recent sexual intercourse. The proportion of Japanese students who used a condom is high in comparison to that of students in other countries. However, as students are prone to have sexual intercourse with non-steady, casual partners, more efforts are needed to promote safe sex practices among college students in Japan.