The concept that lipoprotein(a) [Lp(a)] is a surrogate for ascorbate is suggested by the fact that this lipoprotein is found generally in the blood of primates and the guinea pig, which have lost the ability to synthesize ascorbate, but only rarely in the blood of other animals. Properties of Lp(a) that are shared with ascorbate, in accordance with this hypothesis, are the acceleration of wound healing and other cell-repair mechanisms, the strengthening of the extracellular matrix (e.g., in blood vessels), and the prevention of lipid peroxidation. High plasma Lp(a) is associated with coronary heart disease and other forms of atherosclerosis in humans, and the incidence of cardiovascular disease is decreased by elevated ascorbate. Similar observations have been made in cancer and diabetes. We have formulated the hypothesis that Lp(a) is a surrogate for ascorbate in humans and other species and have marshaled the evidence bearing on this hypothesis.