A comparative study of the metabolic kinetics of organophosphate compounds, biochemical changes and histological changes, in the rat lens during the process of the generating galactose cataract. The change of alpha-glycerophosphate (alpha-GP) with time was analogous to that of dulcitol and the decrease of alpha-GP depended on histological destruction. Furthermore phosphorylcholine decreased considerably before adenosine triphosphate (ATP) decreased, the latter commencing when the histological destruction of the lens progressed to all around the lens. In addition, inositol decreased rapidly after ingestion of galactose. It was concluded that the decrease of alpha-GP was caused by the flow from the lens, and the decrease of ATP started from the epithelium in the lens. Therefore, it was speculated that the decrease of inositol was caused by decrease in the active transport of inositol.