Social learning is a fundamental process through which animals acquire information by observing the experiences of conspecifics. Observational fear learning (OFL) in rodents provides a powerful model to study the mechanisms underlying social memory formation, as observer mice learn to associate a neutral stimulus with the distress of a demonstrator. This paradigm is particularly relevant for understanding disorders involving altered social transmission of information and empathy, such as autism. Previous research has highlighted the oxytocin (OXT) system as a key modulator of social behaviors, yet the specific neural circuits through which OXT contributes to observational fear memories remain poorly understood. We aim to investigate the role of OXT in the formation of observational fear memories, with a specific focus on the hippocampal subregions and the paraventricular nucleus (PVN) as potential key nodes in this process. As a first step, we assessed neuronal activation in dorsal CA1 and CA2 by measuring cFOS-positive cells in observer mice exposed to an OFL training session (TR-Obs), compared to observers whose demonstrators did not receive shocks (noTR-Obs), and to naïve controls. Our results suggest that neuronal activation varies depending on the social experience and differs between sexes, pointing to a potential interaction between OXT signaling, hippocampal circuits, and sex in observational fear learning.