Non-toxic concentrations of ceftazidime (CAZ), cefuzonam sodium (CZON) and cefmetazole sodium (CMZ) for intravitreal use were assessed by the electroretinogram in in vitro perfused eyecups of albino rabbits. None of the a-wave, the b-wave and the oscillatory potentials deteriorated with 300 microM CAZ, 300 microM CZON or 500 microM CMZ. The oscillatory potentials were delayed and/or diminished at the concentration which did not change the a- and b-waves (500 microM and 1.0 mM for CAZ and CZON, 1.0 mM for CMZ). Thus, the oscillatory potentials were more vulnerable to these chemicals than the a- and b-waves. Not only the classical a- and b-waves, but also the oscillatory potentials should be examined in retinal toxicology studies by the electroretinogram.