The clinical and laboratory features of genetic hyperlipoproteinaemia (HLP) in 10 black patients attending the Lipid Clinics at Groote Schuur Hospital and Red Cross War Memorial Children's Hospital are reported. Five had type III HLP characterized by severe cutaneous xanthomas, which facilitated initial detection. Three adult patients suffered from heterozygous primary hypercholesterolaemia compatible with the diagnosis of familial hypercholesterolaemia (FH) caused by a low density lipoprotein receptor defect. They differed, however, from the typical presentation in lacking the Achilles tendon xanthomas characteristic of this condition. One patient presented in childhood with an unusual form of homozygous FH; the remaining patient had type V HLP. Seven of the 10 patients were male and most had risk factors for atherosclerosis in addition to the HLP. Despite the fact that the average age of the 9 adult patients is at present 52 years, only 1 has manifested overt atherosclerotic vascular disease. Compliance with therapy was variable but a generally satisfactory response was obtained in about half the patients, the reduction of plasma lipids in the type IIa subjects being disappointing. These data point to an important area for future study.