Objective: Oral cytology is becoming increasingly important in the early diagnosis of oral cancer, including epithelial atypia. The aim of this study is to assess the whether the cytoplasmic diameter, nuclear diameter and their nuclear to cytoplasmic ratio are reliable parameters in exfoliative cytology in detecting premalignant and malignant lesions. Study design: Cell and nuclear diameter were measured from the squames of normal buccal mucosal and of oral leukoplakia, oral submucous fibrosis, oral lichen planus which were histologically benign and oral squamous cell carcinoma were measured using an ocular micrometer disc. The nuclear to cytoplasmic ratio in each of these were deduced from the values obtained and compared with the controls which were age, sex and site matched. The data were evaluated using statistical methods, namely‘t’ test and analysis of variance. Results: We obtained a statistically significant reduction in the mean cytoplasmic and nuclear diameter in all the four groups. The nuclear to cytoplasmic ratio revealed to be significant only in group 1, 2 and 4. Conclusion: The present study suggests that a decrease in the mean cytoplasmic diameter of exfoliated buccal mucosal cells could serve as an early indicator of dysplastic change especially in lesions which appear histologically benign.