We studied 29 patients on dialysis for terminal uremia, of whom one showed a dramatic rise in intraocular pressure (IOP) during dialysis. We examined the blood pressure (BP) and body weight (BW) before and after treatment in each patient and visual acuity by gonioscopic examination and optic disk status. After dialysis the statistically significant fall in BP and BW was observed in all patients, and in 28 subject an significant rise in IOP was noted. Only one patient experienced a dramatic rise in IOP, and he was the only one suffering from angular glaucoma during the last two years. All this time he was continually treated for glaucoma. After dialysis his IOP was 45 mmHg. With the adequate medication, his IOP lowered to the point when he was able to bear iridectomy which was done with argon and YAG laser. After the surgery his IOP reached the normal values. His visual acuity was good (1.0), visual field was normal, gonioscopic findings showed a narrow angle (Shaffer I, with normal pigmentation), and the optic disk had no abnormalities. It is not yet clear what was the cause of IOP rise during dialysis. It might be that the increased production of aqueous humor, which has been reported in such cases, might be caused by imbalance between blood and aqueous osmolality. If dialysis causes decrease in blood osmolality and if, at some time, blood becomes hypotonic in relation to ocular fluid, then the regular osmotic forces transfer the fluid to the ocular fluid into the eye. This case suggests that all patients on dialysis should undergo a minute ocular anamnesis and examination, and if needed administered adequate medication during the treatment.