Dopamine plays an important role in visual function and retinal sensitivity control. Its actions are mediated through two subfamilies, D1- and D 2-class receptors that are positively and negatively linked to adenylyl cyclase, respectively. However, the data about the specific D1- and D 2-class receptor contribution to retinal responses to light increments and decrements (ON and OFF responses, respectively) are contradictory. A possible explanation might be that many of the results were obtained using non-selective dopamine antagonists and within a limited stimulus intensity (I) range. In this work, the effects of selective blockade of D1-class receptors by 10 μM SCH 23390 and D 2-class receptors by 40 μM sulpiride applied in isolation or in combination on the intensity-response (V – log I) functions of the electroretinographic (ERG) ON (b-wave) and OFF (d-wave) responses were studied. The electroretinograms were obtained from dark-adapted frog eyecup preparations (Rana ridibunda; for details see Popova and Kupenova, 2009). By using a very wide range of stimulus intensities (11 log units, Imax = 6 ×108 quanta. s-1. μm -2), we obtained both rod- and cone-dominated responses. During the isolated D1-class receptor blockade by SCH 23390, the amplitude of both the b- and d-wave was increased (Two-way ANOVA p<0.000001, n=10). During the isolated D2-class receptor blockade by sulpiride, a significant enhancement of the b- and d-wave amplitude was seen in the lower intensity range, where rod-dominated responses were obtained (Two-way ANOVA, p<0.00003, n=11). The amplitude of the two waves was, however, diminished in the higher intensity range (It > -5), where cone-dominated responses were obtained (Two-way ANOVA, p<0.0000002). A similar effect on the b-, but not d-wave amplitude was seen during the combined application of SCH 23390 and sulpiride. The d-wave amplitude was enhanced over the whole except for the highest intensity range (It > -3.5) during the combined D1 and D2 receptor blockade (n=15). The results obtained indicate that the endogenous dopamine has an overall inhibitory action on the rod-mediated ERG ON and OFF responses, but its action on the cone-mediated responses shows clear ON-OFF asymmetry. It is excitatory upon the ON responses, but inhibitory upon the OFF responses except for those in the highest intensity range. Participation of different types of dopamine receptors (predominantly D2-class for the ON versus D1-class for the OFF response) is probably responsible for this difference.