Objectives To examine cytoplasmic cyclin D1 expression levels in oral carcinogenesis and evaluate their possible oncogenic significance and their clinicopathological and prognostic implications. Materials and Methods Immunohistochemical analysis of 69 oral squamous cell carcinomas (OSCCs) was performed, revealing 23 with cytoplasmic cyclin D1 expression. We analyzed the association of the percentage of cyclin D1‐positive cells and the intensity of expression with TNM classification, tumor stage, differentiation degree, cell morphology, and Ki‐67 expression. Results Cytoplasmic cyclin D1 expression was associated with advanced tumor stage, poor differentiation, elevated Ki‐67 expression, and the presence of invasive cell morphology, indicators of a poor prognosis. An association was observed between nuclear and cytoplasmic expressions of cyclin D1. Conclusions Cytoplasmic expression of cyclin D1 appears to possess functions related to increased cell migration and invasion in OSCC.