The authors investigated the relationship between the activity of the renin-angiotensin-aldosterone system and serum lipid levels in patients with essential hypertension (EH). They examined 72 patients with EH stage I and II WHO classification (group A, n = 72, age bracket 16-70 years). They investigated the plasma renin activity (PRA), plasma aldosterone (PA) and total cholesterol (TCH), HDL, LDL cholesterol and triglycerides (TG). They divided the group into three sub-groups according to the PRA into low (L), normal (N) and high renin groups (H) In the whole group they did not find significant differences in the lipid levels in relation to PRA. They selected from the group patients older than 40 years (group B) and in those they recorded significantly higher TCH levels in group H as compared with normal (N) (p < 0.05) and L (p < 0.05) and significantly higher LDL levels in group H as compared with L (p < 0.01). They found a significant direct relationship between PRA and TCH (p < 0.05) and between PRA and LDL (p < 0.01), a liminal relationship between PA and TCH (p = 0.05). They did not find a significant relationship between the RAAS activity and HDL or TG. The authors conclude that patients with EH above 40 years and high PRA a markedly greater hyperlipoproteinaemia as compared with the low- or normal-renin group. This may partly explain the higher incidence of cardiovascular complications in high-renin EH reported by some authors.