With the objective to evaluate the contemporary empirical diagnosis of congenital adrenal hyperplasia (CAH) the authors analyzed data on 50 patients with P450c21 (21-hydroxylase) from four paediatric endocrinological departments in the Czech Republic. In the whole group of patients the ratio of girls to boys was 2.33 : 1 (p < 0.05). In the sub-group of children with salt-wasting CAH (n = 32) the predominance of girls was 2.56 : 1 (p < 0.05), whereby the age at diagnosis did not differ in this sub-group of children between the two sexes (girls - median 0.6 months, boys - median 0.7 months). With regard to the expected rate in both sexes 1 : 1 in autosomal recessive transmission of the disease in the investigation some 60% affected boys were short. With regard to the expected incidence of CAH 1 : 10 000 to 1 : 15 000 of liveborn infants it may be assumed that during the last decade some 30 affected boys died from metabolic collapse, probably before the diagnosis was established. The fate of future children with CAH can be markedly improved by blanket neonatal screening of CAH by assessment of 17 alpha-hydroxyprogesterone in a dry blood drop.

        Key words: congenital adrenal hyperplasia, sex ratio, clinical diagnosis, neonatal screening