Parvalbumin inhibitory interneurons (PV-INs) are a crucial subclass of cortical interneurons, essential for maintaining excitatory/inhibitory (E/I) balance. Disruptions in E/I balance can impair learning, memory, and normal brain function. PV-INs are particularly susceptible to various insults, potentially leading to pathological conditions such as schizophrenia, epilepsy, autism, and Alzheimer's disease. However, the role of PV-INs in these disorders is not fully understood. Our research has identified sex differences in the vulnerability of retrosplenial cortex (RSC) PV-INs under conditions like Alzheimer's disease, traumatic brain injury, and early life stress. This study aims to investigate sex differences in PV-IN characteristics under normal healthy condition—such as number, connectivity, and function—in the RSC of healthy mice, which may underlie differential vulnerability between sexes. Here, we found that both female and male mice exhibit similar RSC neuronal activity levels, indicating no impairment. However, female mice have fewer PV-INs compared to males, and their PV-INs are less frequently surrounded by protective perineuronal nets. Additionally, female PV-INs have more presynaptic contacts per cell than males. This suggests a compensatory mechanism in females, where lower PV-IN numbers with increased synaptic connections allow them to maintain equivalent levels of inhibition. This pattern indicates that despite fewer PV-INs, females may have adaptive advantages that mitigate the impact of reduced PV-IN numbers, contributing to their resilience against certain pathological conditions.