Using previously collected plasma samples, studies were conducted on the distribution of homocysteine and prevalence of hyperhomocysteinemia with emphasis on race, sex and age. Investigations were undertaken on the extent of the relationship of hyperhomocysteinemia to folate and vitamin B12. Finally, the relationships were described between prevalence of hyperhomocysteinemia and prevalence of cardiovascular disease and the importance of this risk factor as a cause of vascular disease among US adults was assessed..