This study was performed to determine whether there were retinal changes in Parkinson's disease. Photopic and scotopic Flash ERGs were conducted for 21 patients with Parkinson's disease and for 19 control subjects. Seventeen patients were medicated with anticholinergics and L-dopa containing drugs. Five findings were observed from the study. 1. There was no difference in implicit time of photopic and scotopic a-and b-waves between the control and the Parkinsonian groups (p(t)>0.05). 2. Amplitude of photopic b-wave was smaller in the Parkinsonian group than the control group (p(t)<0.05). 3. Amplitudes of photopic and scotopic a-and b-waves did not differ between the control and the medicated Parkinsonian groups (p(t)>0.05). 4. Amplitudes of photopic (p(t)<0.001) and scotopic (p(t)<0.01) b-wave were smaller in the nonmedicated Parkinsonian group than the control group. 5. Age and sex characteristics did not affect the results in either group. From the above findings, it is suggested that there is a retinal cell change responsible for b-wave generation in Parkinson's disease, and it is reversed by anti-Parkinsonian medication.