Activation of hippocampal inhibitory pathways is essential for maintaining the balance between excitation and inhibition during hippocampal information processing. Somatostatin (SOM) and Parvalbumin (PV) positive GABAergic neurons are two major classes of interneurons in the hippocampus, providing strong dendritic and peri-somatic inhibition to excitatory neurons, respectively. It is well known that exposure of mice to an enriched environment (EE) reliably increases performance on hippocampus-dependent learning and memory tasks. However, the mechanisms underlying the behavioral improvements and the effects of EE on inhibitory synaptic transmission remain unknown. Therefore, we sought to study the effect of two weeks of EE on inhibition mediated by SOM and PV interneurons onto principal neurons (PNs) of the mouse hippocampus.By using in vitro whole-cell recordings combined with optogenetics in acute hippocampal brain slices, we discovered that EE leads to a substantial increase of the SOM- and PV-mediated inhibitory postsynaptic currents (IPSCs) onto PNs. Systematic mapping of the distance dependence revealed a specific increase of lateral inhibition at distances of more than 200 μm from the optogenetic stimulation site. To assess the activity of PNs in vivo, we performed cFos-labelling in adult mice, after exploration of a novel environment. Interestingly, cFos-expression in PNs was decreased in animals living in cages with environmental enrichment.These findings suggest that EE promotes lateral feedback inhibition of hippocampal PNs to maintain E/I-balance during periods of enhanced hippocampal information processing.