Congenital adrenal hyperplasia (CAH) due to steroid 11-beta hydroxylase deficiency (11beta-OHD) is a rare genetic disorder of steroidogenesis transmitted as an autosomal recessive trait. We describe a new case of 11beta-OHD CAH caused by compound heterozygosity for a novel mutation in intron 7 and previously described mutation in exon 8 of CYP 11B1 gene. A 2.5-year-old boy of Croatian descent presented with accelerated growth and bone age, borderline hypertension, and pseudoprecocious puberty. Hormonal studies established diagnosis of 11beta-OHD: elevated plasma levels of 11-deoxycortisol, 17-hydroxyprogesterone, androstenedione and testosterone, low levels of cortisol and aldosterone, and suppressed plasma renin activity. Sequencing of the CYP11B1 gene identified compound heterozygous mutation consisting of a novel splicing mutation in intron 7 (IVS 7DS+4A to G) and R448H mutation in exon 8 previously reported mostly in Moroccan Jews. This is the first patient with CAH due to 11beta-OHD in Croatia (and Slavic population in general) in whom molecular diagnosis of CYP11B1 gene was performed.