Lenticular reduced glutathione, diminished in all forms fo human cataract, requires flavin adenine dinucleotide as a coenzyme for glutathione reductase. Deficiency of riboflavin, a precursor of flavin adenine dinucleotide, has been believed by some to be associated with cataract formation. We evaluated the riboflavin nutritional status of healthy young adults, presenile and senile cataract patients, and young and older patients with clear lenses. We found no evidence of an association between riboflavin deficiency and early cataract formation, either idiopathic or secondary. Older cataract patients had more riboflavin deficiency. An absence of riboflavin deficiency was found in our older patients with clear lenses. The degree of riboflavin deficiency encountered in the general population does not appear to be cataractogenic.