Introduction and Objectives: Sex workers and their clients have been designated as target groups for individual AIDS control measures, yet no studies have looked at the perspectives of male clients in Japan. The purpose of this study is to assess the HIV/STDs prevention attitudes and practices of men who utilize sex entertainment services. Additionally, the socio-cultural factors of infection vulnerability and needs for preventive measures are examined. Methods: A questionnaire was distributed through one of Japan’s most popular men’s weekly magazines. Male readers who have utilized sex entertainment services were asked to respond to items including types of services they have used, frequency of use in the last year, reasons/motivation for utilization, condom use, HIV anti-body test experience. Using attached postcards, 2,124 men responded. Results: The private bath house (69.8%) was the most popular setting. Types of services received at least once include vaginal intercourse with condom (68.5%), vaginal intercourse without condom (43.4%), fellatio with condom (40.1%), and fellatio without condom (64.8%). 58.9% used condoms while receiving a service during the last year, but only 35.9% of all the respondents answered that they would always use condoms when utilizing the services. 25.1% of all the respondents have been or are currently infected with STD(s) and 23.8% have received an HIV-antibody test. Discussion: Previous studies have shown that sex workers lose control over safer sex practice when their clients were uncooperative. Similarly, the current study indicates that knowledge and attitudes of male clients could lead to the risk of their sexual health and their partners’, including sex workers. The results of this study will guide the development of a secondary study with over 1,000 respondents who indicated a willingness to participate in follow-up interviews.