Research on LGBT health services is urgent as well as effective actions. Some studies investigating the attitudes of mental Health Care Professionals (HCPs), social workers, medical trainees and professionals, students, and resident assistants towards Lesbian and Gay (LG) people showed a significant negative role of sexism affecting attitudes towards LGBT people, marriage and parenting. This study aimed to investigate the influence of Educational Programs in Sexology (EPS) on sexism, homophobia, and attitudes towards same-sex marriage and parenting. Data were collected on 552 Health Care Professionals (HCPs). The EPS group was composed by professionals who attended an accredited training in sexology, while the control group by HCPs without a specific formation on sexual issues. The EPS group reported lower levels of sexism and homophobia and more positive attitudes toward same-sex families (adoption for homosexual couples, artificial insemination and in vitro fertilization for lesbians). Having a specific training on sexology appeared to be associated to more positive attitudes based on equal rights. Healthcare system should be prepared to meet sexual minorities needs. Having a specific training on LGBT issues appears to be functional to a better patients’ taking care. Professionals who attended EPS seem to be the best references (for their formation and their personal attitudes) for sexual education programs, as well as for clinical work with homosexual patients complaining about sexual, marital, and/or parenting problems. Implications for research, clinical and health promotion are discussed.