Human lenses of three different ages were used to study the effect of age and aspirin treatment on glycation of α-, β- and γ-crystallins. Soluble lens proteins were subjected to in vitro glycation with 5 m M [<sup>14</sup>C]glucose in the presence and absence of 10 m M aspirin. With crystallins from a 27-year-old lens α-crystallin was the most readily glycated protein. Glycation of all crystallins decreased substantially (37-77%) in 46- and 67-year-old lenses indicating an age-dependent decline in glycation sites. On the basis of a sensitive chemical assay for protein-bound glycogroups in lenses of 2-82 years of age this decline is apparently due to a 60% increase in in vivo glycation. Aspirin did not show any selectivity with regard to its ability to inhibit glycation of various crystallins. Irrespective of the age glycation of all crystallins was inhibited to a varying extent.