Soft poly(hydroxyethylmethacrylate) gel contact lenses soaked with a solution containing either radioactive sulphate or D-glucose-14C were applied to the rabbit eyes for time intervals ranging from 10 min to 24 h. It was estimated that the radioactive substances were released very rapidly from the contact lens; about 90% within the first hour of application. Radioactivity was then detected in the cornea, aqueous humour, crystalline lens, and vitreous in amounts decreasing with the duration of the experiment. A stepwise accumulation of radioactivity in the eye tissues and fluids was observed with sulphate but not with glucose.