<i>Context:</i> The very high carrier frequency of 21-hydroxylase deficiency worldwide has been postulated as indicating a survival advantage. The ‘mediators’ of such an effect remain speculative. <i>Objective:</i> To look for possible differences in the metabolic and atherogenic risk profile of carriers and noncarriers of <i>CYP21A2</i> gene mutations at puberty in order to identify possible mediators of the presumed survival advantage for the carriers. It is anticipated that by studying atherogenic risk factors at such an early developmental stage, age-related alterations in these factors may be minimized. <i>Methods:</i> The study group included 45 adolescent girls diagnosed in our center with premature pubarche, 29 of whom were noncarriers and 16 carriers of <i>CYP21A2</i> mutations. The two groups did not differ in chronological age, age at pubarche or menarche, pubertal stage, body mass index and waist-to-hip ratio. Biochemical and hormonal profile markers as well as markers of endothelial dysfunction were determined by appropriate methodology. Additionally, in each subject, an oral glucose tolerance test and a gonadotrophin-releasing hormone GnRH analogue stimulation test were carried out. <i>Results:</i> Endothelin-1 values were lower in the carriers compared to the noncarriers (p = 0.031). Higher tissue plasminogen activator and lower plasminogen activator inhibitor-1 values were found in carriers compared to noncarriers (p = 0.02 and <0.001, respectively). The ratio of the insulinogenic index/homeostasis model assessment for insulin resistance, which reflects β-cell function, was higher in carriers (p = 0.048), indicating a more favorable β-cell function in the carriers. <i>Conclusions:</i> Our findings that carriers of <i>CYP21A2</i> gene mutations have a more favorable internal milieu with regard to the metabolic syndrome and atherogenesis support the theory that heterozygous <i>CYP21A2</i> mutations provide a survival advantage. The mechanisms involved may be related to the insulin secretion-action pathway, hypothalamic-pituitary-adrenal axis responsiveness or other still unrecognized factors.