Apo E phenotype and plasma Tg, Chol, LDL-Chol, HDL-Chol and Apo B levels were determined in a sample of 228 healthy Italian subjects (124 men and 104 women) aged 18-93. The allele frequencies were: epsilon 2 = 0.070; epsilon 3 = 0.829; epsilon 4 = 0.101 (among the lowest values in the literature). Division of the sample into four age groups indicated that epsilon 4 frequency decreased with age to 0 in persons aged over 75. Covariance analysis of the influence of each allele on plasma lipids showed that epsilon 4 was significantly associated with the highest Chol, LDL-Chol and Apo B levels. These data are evidence of the influence of epsilon 4 on Chol metabolism in an Italian population. They also show that its frequency decreases with age.