In calf lenses, cow lenses and human senile cataractous lenses, the contents of iron, copper, zinc, magnesium and calcium were analyzed by the atomic absorption spectrophotometry. Bovine lenses showed regional variations in the elementary contents, in that the zinc and iron contents were highest in the anterior cortex of both calf and cow lenses and lowest in the nucleus, and that copper, magnesium and calcium contents in the superficial parts were higher than those in the nucleus in both calf and cow lenses. Bovine lenses showed such variations in elementary contents, tending to increase with age, but copper, magnesium and calcium contents registered no variations specifically associated with age, with no significant difference between the calf and cow lenses. Magnesium content was found to be the highest of alle elements in both calf and cow lenses. In human cataractous lenses, calcium and zinc contents were shown to be higher in completely cataractous lenses than in partially cataractous lenses. Calcium content was found to be particularly high in the former group. No significant difference was found in iron, copper or magnesium content between the two groups.