ABSTRACT Background and aim: The inducible stress protein, heme oxygenase‐1 (HO‐1) is considered to be a mediator of cytoprotective processes that might be of particular significance during inflammatory events. Currently, there is nothing in the literature regarding HO‐1 expression and proliferation in oral lichen planus (OLP). We investigate whether HO‐1 and proliferation are more expressed in the tissues of OLP patients compared to normal tissues. Methods: Streptavidin‐based immunohistochemical staining was used to detect proliferating cell nuclear antigen (PCNA) and HO‐1 in 36 cases of OLP. Results: In OLP, HO‐1 was found to be expressed in basal and parabasal dendritic cells and lymphocytes and was coincident with PCNA expression. PCNA and HO‐1 immunoreactivities were higher in OLP mucosa than in normal mucosa, and the differences were statistically significant. Conclusions: These results suggest an elevation of HO‐1 expression in OLP. HO‐1 may play an adaptive or cytoprotective role during the immunologic stress of OLP.