Objective: In this study, the subclinical involvement in visual pathways were investigated by means of pattern reversal visual evoked potentials (PVEPs) in chronic hemodialysis (HD) patients and the short-term effects of HD on PVEPs were evaluated. Methods: PVEPs were recorded in 20 healthy subjects and in 18 patients who had no neurological and/or ophthalmological involvement on clinical examination. In patient group PVEPs were performed 2 hours and 26 hours after two sets of HD performed 4 months apart. Urea, creatinine and electrolytes were measured immediately before each PVEP examination. Pathological tresholds for individual P100 values were set at 3SD above the control means for both absolute latencies and interocular latency differences. Results: Abnormalities regarding the P100 latencies could be detected in 23.5% of the patients. When compared the group mean values of patients with normal PVEPs, P100 latencies did not reveal any significant change between two tests in each admission. P100 amplitude was significantly higher in 2nd hour examination than in 26th hour examination only at second admission. There was no relationship between amplitudes and biochemical measurements. P100 latencies showed a significant correlation with urea measurements in one occasion and with creatinine in another occasion. Conclusion: Standard PVEP examination can be beneficial in detecting subclinical abnormalities in HD patients. HD could have short-term effects on P100 amplitudes though this effect could not be established consistently and did not correlate with biochemical parameters.