Both lipids and inflammation sensitive proteins have been reported to affect the aggregation of red blood cells yet their relative importance in this regard have not been determined. We have included high sensitive C-reactive protein, erythrocyte sedimentation, fibrinogen concentrations as well as various serum lipid concentrations and the degree of erythrocyte adhesiveness/aggregation in the peripheral blood in a linear regression analysis. Partial Pearson correlation coefficients were included as well. In a group of 674 individuals with various atherosclerotic risk factors, low grade inflammation and moderately increased serum lipids, a relatively low correlation was noted between red blood cell adhesiveness/aggregation and triglycerides concentrations. A negative correlation was noted for HDL cholesterol. None of the lipid variables turned significant in the regression analysis. In a group of individuals with atherosclerotic risk factors, low grade inflammation and moderately increased serum lipids, the degree of erythrocyte adhesiveness/aggregation in the peripheral blood correlates much better with the presence of inflammation sensitive proteins than with the presence of increased lipid concentrations.