The present systematic review aimed to determine discrimination experiences of sexual and gender minority (SGM) individuals and attitudes toward SGM among health care staff in health care settings. Following PRISMA guidelines, the review was conducted in 3 databases (PubMed, Cochrane Library, Science Direct) using keywords of sexual and gender minority, including “gay,” “lesbian,” “bisexual,” “transgender,” “LGB,” “LGBT,” “health care discrimination,” “stigma,” “homophobia,” “transphobia,” and “attitudes of healthcare professionals” from May to September 2016. Predetermined inclusion criteria were selected. Thirty quantitative studies were eligible for inclusion in this review. Discriminative behaviors experienced by SGM individuals were stigma, denial or refusal of health care, and verbal or physical abuse. Knowledge and educational levels, beliefs, and religion of health care providers affected their attitudes toward SGM patients and their homophobia level. These findings revealed that health care providers needed more education about SGM issues, and SGM-friendly policies should be created for improving health care for SGM individuals.