Intra- and extracellular acidosis are ubiquitous events in cerebral ischemia. In neurons intracellular pH is mainly regulated by the Na⁺/H⁺ exchange system. Inhibition of Na⁺/H⁺ exchangers has been intensely studied in models of myocardial ischemia, but there are not many reports available on cerebral ischemia. In the present study we investigated the effects of inhibition of Na⁺/H⁺ exchangers on ischemic damage in organotypic hippocampal slice cultures (OSCs) from 10-day-old rats and acute hippocampal slices from adult animals. The broad-spectrum Na⁺/H⁺ exchange inhibitor harmaline reduced neuronal cell death in slice cultures both when present during the insult and the recovery period as well as when applied only during the recovery period. The protective effect of harmaline was mimicked by the more specific inhibitors EIPA and S3226, but not by typical inhibitors for the Na⁺/H⁺ exchanger isoform 1, indicating that the protective effect is not mediated by this isoform. Harmaline also protected organotypic cultures from neonate rats but, contrasting EIPA, not acute hippocampal slices from adult animals against functional neuronal damage. This may indicate that the protective effects involve different Na⁺/H⁺ exchangers. Also supporting the notion that regulation of intracellular pH is developmentally regulated, EIPA did not affect the recovery from an acid load in isolated neurons from neonate rats, although EIPA sensitive Na⁺/H⁺ exchangers were expressed. Our data show that Na⁺/H⁺ exchange inhibition can protect hippocampal neurons from oxygen-glucose-deprivation induced injury. We speculate that the protective effects are either due to the suppression of pH-sensitive injury mechanisms or to a restriction of Na⁺ entry, which would limit subsequent Ca²⁺ accumulation via the Na⁺/H⁺ exchanger.