Members of the lesbian, gay, and bisexual (LGB) community experience significant health disparities. Widespread preferences for heterosexual over homosexual people among healthcare providers are believed to contribute to this inequity, making recognition (and ultimately reduction) of healthcare providers' sexual prejudices of import. The present study sought to characterize North American genetic counselors' and genetic counseling students' implicit and explicit attitudes toward homosexuality. During January 2017, 575 participants completed a Web-based survey and Sexuality Implicit Association Test (SIAT). A majority of participants (60.2%) harbored implicit preferences for heterosexual over homosexual people. Mean implicit attitude score (0.24) indicated a slight automatic preference for heterosexual over homosexual people, while mean explicit attitude score (0.033) indicated no preference for either group. Although participants' implicit and explicit attitudes were positively correlated (p < 0.001), there was greater implicit bias for heterosexual over homosexual people than suggested by explicit attitude scores (p < 0.001). Implicit attitudes differed across self-reported sexual orientation (p < 0.001), but not across gender, race, or genetic counseling specialty. Education has been demonstrated to be moderately effective at reducing sexual prejudices, and almost all participants (95.8%) indicated that they would support the implementation of genetic counseling curricula addressing lesbian, gay, bisexual, and transgender (LGBT) issues. The study's combined findings suggest that North American genetic counselors and genetic counseling students support, and may benefit from, the implementation of genetic counseling curricula addressing LGBT issues.