Electroretinograms (ERG) obtained before and during chloroquine therapy have been compared. The results showed an increase in the amplitude of A, X and B waves. These results are in contradiction with those of other authors having reported that A and/or B waves decreased in cases of lesions of the retina due to the chloroquine. Such discrepancies may be due to the fact that ERG were recorded at different stages of impregnation of the retina by the chloroquine, and perhaps, because of a specific and early impregnation of the ganglion cells. It seems absolutely necessary to record the ERGs regularly in order to detect when the waves begin to decrease, since this may be the threshold of a real intoxication.