The mouse accessory olfactory system (AOS) plays a central role in the detection of chemosignals during social interactions of conspecifics. Along the accessory olfaction pathway, the first central stage of information processing is the accessory olfactory bulb (AOB), which consists of projection neurons (mitral cells) and local interneurons, i.e., granule cells and periglomerular cells (PGCs). AOB mitral cells receive excitatory synaptic input from vomeronasal sensory neurons in multiple glomeruli. These glomeruli are surrounded by PGCs. While PGCs may serve to attenuate the input strength, their actual physiological function remains unknown. Here, we detail the biophysical properties of PGCs. In order to investigate cell type-specific features, we perform whole-cell patch-clamp recordings from visually identified PGCs in acute slices of the mouse AOB. We analyze passive and active membrane properties, voltage-activated currents, and action potential firing. The results reveal neurons with unique properties and, thus, provide first insights into the physiological characteristics of PGCs in the mouse AOB. Ongoing research will continue to shed light on the physiological principles of sensory processing in the AOB network.