BACKGROUND: Deficiency of 17β-hydroxysteroid dehydrogenase type 3 (HSD17B3) is a rare variant of 46,XY disorders of sex development (DSD).AIM: To give clinical, hormonal and molecular genetic characteristics of cases of 46,XY DSD associated with variants in the HSD17B3 gene.MATERIALS AND METHODS: The study included 310 patients with 46,XY DSD for the period from 2015 to 2019. This evidence concerns the gene HSD17B3 and disorder of sexual differentiation.