alpha-Crystallin can function as a molecular chaperone by preventing unwanted interactions. This paper presents the effects of aging and cataract on the chaperone-like properties of alpha-crystallin from soluble fractions from the cortex and nucleus of human lenses by using three assays: enzyme inactivation and two turbidity experiments. The three methods complemented each other. There was no decrease with age of chaperone-like function of cortical alpha-low and alpha-high crystallin. Nuclear alpha-low crystallin showed a decrease, whereas alpha-high crystallin showed no age-related change but its protective effect was diminished. Results from the nucleus of 40-year-old cataractous lenses seemed similar to those for clear lenses of equivalent age, whereas 80-year-old cataractous lenses showed decreased chaperone-like behaviour.