Despite the suspected large numbers of bisexually oriented people, there has been almost no research on bisexuality. More important, the research on homosexuality is thoroughly confounded by the inclusion of large numbers of bisexuals as homosexuals, making that research difficult to interpret. The few studies of bisexuals that have been done are reviewed in this paper. Comparisons show that bisexuals often significantly differ from homosexuals and heterosexuals. Therefore, the practice of combining bisexuals with homosexuals in studies of homosexuals should be discontinued. Comparison studies of bisexuals, heterosexuals, and homosexuals are recommended.