The clients of Female Sex Workers (FSWs) have been represented from different socio-demographic backgrounds and their risk behaviour depends upon their learning skills and attitudes and its impacts on practice. The general objective of this study was to find the socio-demographic characteristics, background, knowledge, behaviour, and the attitude on STIs, HIV and AIDS of the clients of female sex workers. This questionnaire based, cross sectional study was conducted on 109 clients of FSWs during the time period from January 2010 to July 2010 in Pokhara (submetropolitan city of the Kaski district), Nepal. The locations were the Baglung Bus Park, Lakeside and Mahendrapool. Among the 109 respondents, the mininum and the maximum age were 18 and 50 years. According to the religion-wise distribution, 77.1% of the respondents were Hindus, 10.1% were Buddhists, 8.3% were Christians, 1% were Muslims and 3.7% were from other religions. 67.9% of the respondents were tested for HIV at least once, whereas nearly one third (32.1%) of the respondents were never tested for HIV. 49.5% of the respondents answered that there was no difference between HIV and AIDS. Among the respondents, 89.9% respondents knew how to be safe from STIs and the HIV infections and 99.1% knew about HIV and AIDS. HIV and AIDS is a cross cutting issue in the present situation rather than a health issue. One of the most at risk groups is the clients of female workers who frequently have risk behaviours like having sex with female sex workers. The sexual behaviour among these clients depends upon their attitude, knowledge and perception, which also influence several internal and external factors. In our study, the clients of the female sex workers had some extent of knowledge about the condom, sexually transmitted infections and HIV/AIDS. They were made aware on these by different organizations who were working in the field of HIV and AIDS, but still they intended to practise unsafe sex with the female sex workers.