A typical posterior subcapsular cortical cataract was successfully induced in an organ culture of a rat crystalline lens with the addition of 2 X 10(-5)M vincristine sulfate. A similar cataract was also induced by applying microtubule inhibitors such as Colcemid, colchicine, and podophylotoxin. In a posterior subcapsular cortical cataract induced by vincristine sulfate, metaphase arrest was observed both in the organ culture and cell culture of the epithelial cells. The result indicated microtubule inhibition. The findings illustrated such pathological processes as disturbance of the elongation of epithelial cells, development of vacuolar degeneration and Morgagnian droplets in the spaces between lens fibers, and the appearance of cellular debris due to degeneration of the terminals of the lens fibers as a result of microtubule inhibition. Apart from findings in sugar cataracts, sequential changes of cataract development did not include fluctuations of the lens water content up to the 7th day (immediately prior to the development of nuclear cataracts).