Background: Micronuclei are chromatin particles derived from acentric chromosomal fragment, which are not incorporated into the daughter nucleus after mitosis. Exfoliated cells from the oral cavity of carcinogen-exposed individuals have demonstrated increased frequencies of micronuclei. Aim: The aim of this study was to assess the frequency of micronuclei in exfoliated cells from oral precancerous and cancerous lesions and to evaluate the micronucleus test as a screening procedure for precancerous and cancerous lesions. Methods: 120 participants consisting of 40 cases each of controls, oral leukoplakia and oral squamous cell carcinoma comprised the study. All the 120 subjects were subjected to cytosmear for evaluation of frequency of micronucleated cells. Results: Highly significant differences in the MNC frequency were observed between controls, oral leukoplakia and oral squamous cell carcinoma (p < 0.001). Conclusion: Micronuclei assay of exfoliated oral cells could be used in assessing the genomic or cellular damage in individuals who are at high risk for cancer. However, due to overlapping values of the percentage of micronucleated cells (MNC %) in the control and study group, it may be difficult to assess the prognosis of a lesion based on this MNC% alone. Hence MN should be evaluated in combination with other biomarkers for the assessment of increased cancer risk.