Steroid 21-hydroxylase deficiency is the most frequent cause of congenital adrenal hyperplasia (CAH), which is an inherited inability to synthesize cortisol. Actually, CAH is caused by mutations in the CYP21 gene encoding the steroid 21-hydroxylase enzyme. In some cases, discordance has been observed between the genotype and the phenotype. We recently experienced two cases of simple virilizing congenital adrenal hyperplasia with compound heterozygous mutations of the CYP21 gene. The patients had primary amenorrhea and showed virilization. We have described these two cases along with a review of the literature.