Strychnine and picrotoxin were tested as possible antagonists of two puta- tive inhibitory transmitters in the retina: taurine and GABA, Strychnine was shown to antagonize the depressive action of taurine on the ERG b-wave, but it did not affect the depressive action of GABA. Conversely, picrotoxin had no effect on the depressive action of taurine on the ERG b-wave, but it antagonizes to some extent the depressive effect of GABA. These data, as well as those obtained through recording tectal evoked responses, lead to the conclusion that taurine and GABA do not act in the same way in retinal...