The purpose of this study was to examine the experience with attitudes towards, and knowledge about homosexuality of three groups of health care professionals. Subjects were 97 registeres nurses, social workers, and psychologists who responded to a six-page mailed questionnaire. Professional discipline of the subject, gender of the client, and gender of the client's lover in a fictitious scenario did not significantly affect ratings or suggested diagnoses of the client. Most subjects felt that they needed moer training in working with homosexual clients, which was consistent with their high but not perfect scores on a knowledge test. Subject's mean scores of the Attitudes Toward Lesbians (ATL) and Gay Men (ATGM) scales of Herek (1998) reflected significantly less prejudice than his college samples. More knowledgeable respondents were less prejudiced and had more positive attitudes about working with gay and lesbian clients; those with more positive attitudes toward clients also showed less prejudice on the ATL and ATGM scales. The authors argue that training health care professionals to be more knowledgeable about gay and lesbian issues would lead to more positive attitudes and better services for gay and lesbian clients.