PURPOSE: Current guidelines for gender-affirming hormone therapy (GAHT) primarily focus on binary transgender (BT) individuals and provide limited recommendations for non-binary and genderqueer (NBGQ) individuals. Understanding hormone use among this heterogenous group will contribute to more personalized counseling and treatment strategies. We performed a systematic review of the scientific literature to assess the prevalence of GAHT in NBGQ individuals and potential clinical context-dependent differences. METHODS: A systematic literature search was performed aimed to assess the prevalence and type of GAHT use in NBGQ and BT individuals according to Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guidelines, using PubMed, Embase and Web of Science databases. RESULTS: Sixteen eligible articles were identified. All were retrospective cohort series published between 2018-2024, including a total of 1948 NBGQ individuals and 3991 BT individuals. Hormone use varied from 4-93% in NBGQ individuals and from 52-95% among BT individuals. Overall, significantly fewer NBGQ individuals were on GAHT compared to BT individuals, except those referred to gender-affirming care clinics. GAHT was more frequent in clinical cohorts compared with non-clinical cohorts, both among NBGQ (OR 6.4; CI 5.1-8.0) and BT (OR 3.1; CI 2.6-3.8) individuals. There was insufficient Information in the literature to be able to draw conclusions with regard to differences in types of GAHT. CONCLUSION: The systematic review confirms that GAHT is less common in NBGQ compared with BT individuals. Hormone use is more frequent among NBGQ individuals seeking care in a clinical setting. These results highlight the heterogeneity in NBGQ as well as BT individuals with regard to treatment needs. Caregivers, in particular in clinical settings, should be aware that not all NBGQ individuals seek GAHT. Additional studies are needed to further explore tailored endocrine treatment needs in NBGQ individuals.