Postsynaptic density-95 (PSD-95) is one of neuronal nitric oxide synthase (nNOS)-anchoring proteins and plays an important role in specifying the sites of reaction of nitric oxide (NO) in the nervous system. The present study aims to investigate the presence of PSD-95 in rat Schwann cells (SCs) and the association of PSD-95 and nNOS with serum-induced SCs proliferation. The expression of both molecules downregulated significantly after 48 h of serum deprivation, and increased gradually to the peak at 12 h, ultimately returned to the control level at 48 h after serum stimulation. The association of PSD-95 with nNOS was observed in Ki67 and BrdU-positive SCs. The selective nNOS inhibitor arrested the cell cycle progress and decreased the proliferating cell nuclear antigen (PCNA) levels. These findings suggested that PSD-95 and nNOS may collectively participate in the proliferation of SCs, providing further evidence for the role of NO during peripheral nerve regeneration.