The etiology of Alzheimer's disease is now known to be multifactorial. The genetic factors transferrin C2 (TfC2) and apolipoprotein E epsilon 4 (ApoE-epsilon 4) have both been associated with Alzheimer's disease (AD). Transferrin is the carrier protein for iron in the blood, while ApoE is involved with the transport and redistribution of lipids. In the present study, the polymerase chain reaction (PCR) method was used to determine the frequency of both TfC2 and ApoE-epsilon 4 in 27 AD patients, 9 vascular dementia (VaD) patients, and 27 controls. Patients were diagnosed according to the criteria as set out in the 4th edition of the Diagnostic and Statistical Manual of the American Psychiatric Association (DSM-IV). The frequency of the TfC2 allele for the AD patients was 24%, while for the VaD patients it was 12.5%, which was not significantly different from the controls at 13%. The frequency of ApoE-epsilon 4 for the AD patients was 44%, for the VaD patients 22%, and controls 17%. Of the 27 AD patients, 8 had both TfC2 and ApoE-epsilon 4. The age of onset of the disease in these 8 patients (51-67 years, mean 60.25) was significantly earlier (p < 0.02) than in the remaining AD patients (49-76 years, mean 66.9). None of the VaD patients had both the TfC2 and the ApoE-epsilon 4 alleles.