Daunomycin action on human lens epithelial cells has been tested in vitro, with different exposure times. A clinical study on 30 eyes, operated on by the same surgeon, has been carried out according to the Cologne protocol. Cell cultures, with different techniques were grown. This demonstrates that Daunomycin can destroy the lens epithelial cells. We can not currently say what dosage and protocols are necessary to achieve a prevention of secondary cataract.