Background: Steroidogenic factor-1 (SF-1) gene (NR5A1) mutations cause disorders of sexual development due to gonadal dysgenesis, particularly in 46,XY individuals. In cases exhibiting this mutation, the phenotype is heterogeneous, and it may vary within a spectrum ranging from complete female appearance to an infertile male. Virilization observed in some cases in the pubertal age group may lead to diagnostic difficulties. Case: The present case report describes the clinical, histopathologic, and genetic characteristics of a 46,XY case, who was born with a female phenotype and raised as a girl, presented with findings of virilization in the pubertal period. She had no germ cells and very few Leydig cells with atrophic testis on biopsy and in whom a novel heterozygous mutation in the SF-1 gene (a heterozygous 7-bp deletion mutation in exon 7 [c.1308-1314del7bp] causing frameshift) was identified. Summary and Conclusion: Although the gonads are very dysgentic in patient with SF-1 mutations, sufficient androgen synthesis can cause severe virilization during puberty. © 2014 North American Society for Pediatric and Adolescent Gynecology.