© 2014 Elsevier B.V.Deficiency of 17β-hydroxysteroid dehydrogenase type3 (17β-HSD3) isoenzyme which catalyzes the synthesis of testosterone from δ4-androstenedione, is the cause of 46, XY disorders of sex development (DSD). 17β-HSD3 deficiency is a rare autosomal recessive disorder, which is caused by mutations in the HSD17B gene found on chromosome 9q22. Up to now, almost 33 mutations in the HSD17B3 gene have been reported. Here, we report a patient with a novel mutation in HSD17B3 gene leading to 17β-HSD3 deficiency. The patient was admitted because of primary amenorrhea and signs of virilization at puberty. The chromosome analysis showed a 46, XY karyotype. Hormonal evaluation revealed a high δ4-androstenedione level with a low serum testosterone/androstenedione (T/A) ratio. Sequence analysis of HSD17B3 gene revealed the presence of a homozygous missense mutation in exon 11 resulting in a premature stop codon (p.Y287). Gonadectomy was performed after the molecular diagnosis and estrogen replacement therapy was initiated. With this report, we emphasize that 17β-HSD3 deficiency should be considered in virilized female patients at puberty if the T/A ratio is less than 0.8, and the molecular analysis should be performed for the precise diagnosis and genetic counseling.