Oral cancer is a neoplasm with some known causes. Proliferation genes are significant among its few pathogenetic and prognostic factors. Calcyclin is a cell-cycle-related gene, the function of which is still unclear. Its expression and that of Haras and histone-H3 have been investigated in an assessment of their pathogenetic role in squamous cell carcinoma. RNA extracted from the pathological and normal mucosa of patients with squamous cell carcinoma (SCC) and benign lesions was reverse transcribed and amplified by the polymerase chain reaction (PCR). The expression of all three genes in the pathological mucosa was enhanced in SCC only. This suggests that they may be involved in its pathogenesis and provides another parameter for the differentiation of malignant and benign lesions.