The men with the violent criminal record had significantly lower total cholesterol, lower LDL cholesterol, higher apolipoprotein A1, and lower apolipoprotein B compared with the control group. The findings on the link between low cholesterol levels and violent behavior are similar to those in previous studies. The findings on apolipoproteins A1 and B and violence are new. These findings are consistent with the study's hypothesis and with the expectation that higher apolipoprotein A1 and lower apolipoprotein B result in lower serum cholesterol. The authors advise that for these findings to have practical application, more substantial evidence is required on a direct effect of lipid metabolism on human behavior or associations due to a common genetic basis or other factors. Subsequent research findings may have implications for the prison diets of violent offenders. Blood samples after fasting were collected from 30 men with a known history of violent crime and 30 men with no criminal record. Serum lipid profile and serum apolipoproteins A1 and B were measured in each sample and compared between the two groups of men. 1 table and 26 references