We evaluated the retinal toxicity of aminoglycosides (gentamicin, sisomicin, netilmicin, tobramycin and amikacin) by ERG, before and after a single-shot intravitreal injection in rabbits. Gentamicin 200 micrograms abolished the c-wave one week after injection, only slightly diminishing the b-wave and the oscillatory potentials (OPs). Gentamicin 80 micrograms did not alter the ERG up to at least 8 weeks after injection. All the ERG components examined were abolished by 200 micrograms and were irreversibly suppressed by 80 micrograms of sisomicin for the entire period of follow-up. Netilmicin (200 micrograms) or tobramycin (200 micrograms) transiently suppressed the b-wave, c-wave and the OPs. Amikacin (200 micrograms) caused no ERG changes for at least 8 weeks after injection. The clinical doses for single-shot intravitreal injections that we recommend are 100 micrograms for gentamicin, 200 micrograms for netilmicin, 200 micrograms for tobramycin and 200-400 micrograms for amikacin.