Gaucher's disease is the most prevalent sphingolipid storage disease, characterised by substantial genetic and phenotypic variability. Cardiac manifestations are rare. We report 12 Arab Gaucher's disease patients, 2-20 years of age, who presented with oculomotor apraxia but only slight classic signs of the disease. All but the youngest had calcifications of the aortic or mitral valves or both. All these patients were homozygous for the rare point mutation D409H (1342C). Valvular calcifications increased with age and showed progression during 2 years of follow-up. Two of the oldest patients underwent aortic valve replacement, and one sibling had died suddenly at age 16, before this study, Corneal opacities were another common feature. The potentially fatal course of this Gaucher's disease variant, and the availability of a reliable PCR-based method for heterozygote detection, mean that population screening and genetic counselling in the geographic area at risk are important. Affected individuals should be closely monitored by echocardiography to gauge the need for valve replacement. The potential of enzyme replacement to prevent these cardiac complications cannot be ascertained at present, because of the high cost of therapy.