Recently, it was suggested that the presence of total cholesterol (TC), age and sex interaction in Alzheimer's type dementia (AD) is linked with the apolipoprotein E (APOE) genotype. Our objective was to determine whether the serum lipid profile in AD patients and their first degree non-demented relatives of a certain age (NDR) was dependent on APOE genotype. We included 28 mild to moderate AD and 30 NDR according to DSM-III-R and NINCDS-ADRDA criteria. NDR individuals were investigated in an age group similar to the AD group (brother-sister relationship) and in a group including younger individuals (AD patients-children relationship). Our data indicate significant differences between decreased total cholesterol and low density lipoprotein cholesterol ratio in the group of AD patients versus NDR individuals of similar age, independent of APOE genotype, and an increased total cholesterol and low density lipoprotein cholesterol ratio in a group of AD patients versus their children of the same genotype. There was no significant correlation between triglycerides and high density lipoprotein levels with APOE genotype in any of the tested groups. In conclusion, there was a decreased selected lipid serum profile parameters in AD compared to age matched non demented first degree relatives.