OBJECTIVE: 11beta-Hydroxylase and aldosterone synthase are two highly homologous genes involved in different forms of human hypertension and in different animal models of hypertension. It has been shown that the conservative substitution D147E in the human CYP11B2 gene results in an increased production of corticosterone and aldosterone in vitro. A gene conversion between the CYP11B1 and CYP11B2 genes could be responsible for such a substitution. METHODS: In this study we investigated the presence of the mutation D147E of CYP11B2 in a group of 128 patients with primary aldosteronism, 68 patients with essential hypertension and increased corticosterone production and in 48 normal volunteers. RESULTS AND CONCLUSIONS: We did not identify any patient carrying this mutation, indicating that if it exists it is very rare and so has no relevance in determining the increased steroid excretion seen in some subtypes of human hypertension.