There is a growing awareness that internal migration in China might shift the HIV epidemic by broadening the social and sexual mixing of its population. However, little is known about how drug use/abuse might contribute to the spread of HIV. This qualitative study aims to elucidate factors for preventing substance abuse and HIV among two types of male migrants living in the Shanghai metropolitan area; the general migrant population and so-called 'money boys' (those who engaged in same-sex activities for money). Compared to most male migrants, the 'money boys' had a slightly better economic situation; rarely visited their hometowns; used alcohol less but drugs more; had more knowledge about HIV and sexually transmitted diseases; higher HIV/ STD testing rates and fewer HIV risk behaviors. The general male migrants had more misconceptions about HIV (e.g. the need to pay for HIV testing) than the 'money boys'. However, it was noted that 'money boys' who were new to the enterprise and men who have sex with men but did not engage in commercial sex often lacked HIV knowledge and protective skills. Given the needs of various sub-types of 'migrants', differential approaches to HIV prevention are needed.