The hippocampus is a key brain region involved in synaptic plasticity, learning, memory formation, and neurodegenerative disorders such as Alzheimer's disease (AD). Leptin has been recently shown to affect neuronal activity and neuronal survival, thanks to its neurotrophic action. Here we report the effect of hypoxia (3% O2, 2 hours), on the firing pattern of mouse hippocampal primary cultures in the presence and the absence of leptin. The tool used in this study is the Multi Electrode Array (MEA) that allows monitoring the electrical activity of cultured neuronal network. Under normoxic conditions we found that the firing frequency and the number of bursts increased between 11 and 18 DIV. The former increased from 0.8 to 1.8 Hz while the latter from 6.5 to 10 (over 90 seconds recordings), suggesting that in elder cultures, events predominantly occurred during synchronized patterns of activity. Exposure to hypoxic conditions caused a significant reduction of the firing frequency, by 51 ± 3% and 71 ± 2% respectively at 11 and 18 DIV, which was reversed when returning to normoxia. When hippocampal neurons were pre-treated with leptin (50 nM) 1 hour before their exposure to hypoxic conditions, the firing frequency was reduced by only 52 ± 2% at 18 DIV and 49 ± 4% at 11 DIV, suggesting that 50 nM leptin exerts a preferential cytoprotective effect on elder hippocampal neurons (18 DIV) subjected to hypoxic injury.