Different nonsteroidal antiinflammatory drugs (NSAID), especially ibuprofen, are being considered as an alternative to indomethacin for use in the newborn and as antipyretics for infants. However, some of these NSAID have been shown to cause visual complications. We therefore studied the effects of different NSAID indomethacin 19.6 μ-mol/kg (7 mg/kg), diclofenac 15.7 μmol/kg (5 mg/kg), ibuprofen 48 and 194 μmol/kg (10 and 40 mg/kg), naproxen 79 μ,mol/kg (20 mg/kg), and flurbipro-fen 41 μmol/kg (10 mg/kg) on photopic and scotopic electroretinograms (ERG) and retinal prostaglandin E2, prostaglandin F2α, and 6-keto-prostaglandin F1α levels in piglets 1–5 d old. All NSAID decreased retinal prostaglandin levels, but their effects on the ERG were not identical. Indomethacin and diclofenac did not alter the ERG. In contrast, the propionic acid derivatives ibuprofen (the two doses used), naproxen, and flurbiprofen affected the amplitude as well as the implicit time of the ERG under photopic and scotopic conditions. These changes are suggestive of generalized alterations in the function of rods and cones. Prior inhibition of prostaglandin synthesis by indomethacin did not modify the effects of ibuprofen on the ERG. These findings thus show a dissociation between the effects of NSAID on the ERG and prostaglandin synthesis. Because ERG changes are associated with visual alterations, these effects of propionic acid derivatives should be taken into account before considering their use in infants.