[en] Cataracts, produced in 4-week old rats using 185 kVp X-rays and 570 MeV/amμ charged Argon (Ar) nuclei, were studied by light and scanning electron microscopy (SEM) at varying intervals post-irradiation. The severity and extent of the damage varied as an increasing function of dose and correlated well with cataract stage. Damage was generally limited to the equatorial and posterior subcapsular regions. The late stage cataracts were associated with massive disruption of the equatorial region and the formation of a granular matrix which extended to the poles. Ultrastructural changes were noted also in the superficial cortical region, while the lenticular nucleus and the remainder of the cortex remained unchanged