We have previously reported overexpression of p53 protein in tobacco-related oral dysplasia and squamous cell carcinoma (SCC) in the Indian population. A follow-up study was carried out to determine the prognostic significance of an accumulation of p53 protein during oral tumorigenesis. One hundred and two of 145 (70%) of oral SCCs and 39/75 (52%) of oral dysplasias showed overexpression of p53 protein, while only 3 of 107 (3%) normal oral tissues showed a detectable level of the protein. Follow-up studies of these patients suggest that an accumulation of p53 protein may be involved in the early phases of oral SCC development and indicate the predisposition of a particular premalignant lesion towards malignancy. In patients with premalignant lesions, the median transition time (premalignancy to malignancy) was significantly shorter in p53 positive cases than in p53 negative cases (p = 0.013). Among the oral cancer patients, univariate analysis showed that alteration in p53 expression was associated with significantly decreased disease-free survival. The p53 positive cases showed decreased median disease-free survival time (no recurrence/metastasis) compared with the p53 negative cases (p = 0.013), indicating that p53 accumulation may serve as a prognostic indicator in oral cancer patients.