Objective. To evaluate the relationship between the maturation index of vaginal squamous epithelium (as a marker of local sensitivity to estrogens) and the degree of CAH compensation. Methods. 17 adolescent girls with classical form of CAH (salt-wasting (SW) - 8, simple virilizing (SV) - 9, median age of 15.8 (14.9;16.9) years old, Tanner 4 (3;5)) were included in the research. Patients were divided into 2 groups: full compensated (I) and inadequate compensated (II). Pelvic ultrasound and cytological examination of vaginal smears with the determination of karyopyknotic index (KPI), atrophic index (АI) and vaginal maturation index (VMI) were performed. Results. Positive correlation between KPI and uterine volume (rs=0.69, p=0.002), and between VMI and uterine volume (rs=0.82, p<0.001) were observed. VMI negatively correlated with serum testosterone level (rs=-0.6, p=0.009). KPI and VMI were significantly higher in group I than in group II (36.2% (30.8; 38.6) vs. 3.5% (0.0; 31.15), p=0.009 and 62.5% (58.25; 64.5) vs. 47.9% (41.47; 55.25), p=0.003, respectively). AI in group II was significantly higher (8.5% (0.0; 20.25) vs. 0.0% (0.0; 0.0), p=0.007). The significant difference of AI was observed in the group II between SW and SV form (20.25% (10; 33.75) vs. 1.75% (0.0; 8.5), p=0.04, respectively). Conclusion. According to our data, the estrogenization of external and internal genitalia mainly depends on the compensation of CAH. Reduced maturation of vaginal epithelium was more typical in girls with inadequate control of salt-wasting form of the disease compared with simple virilizing form, so these patients need more careful observation in adolescence.