AIM To do a prospective clinicohistological study of premalignant and malignant lesions of the oral cavity, and compare it with a 10-year retrospective data, especially in terms of incidence, age distribution, personal habits, and site and type of lesion. MATERIAL AND METHODS Sections from 776 lesions of the oral cavity, which included 647 lesions of a 10-year (1993 - 2003) retrospective study and 129 lesions of a one-year (2003 - 2004) prospective study, were observed clinically, and a histological correlation was carried out. RESULTS Premalignant lesions included 78 cases of leukoplakia, 68 cases of oral submucous fibrosis, and 76 cases of squamous papilloma. Their incidence has increased in the last decade from 0.15 to 0.53. These lesions commonly presented in the fourth decade of life, as white patches in leukoplakia and oral submucous fibrosis, and as a growth in squamous cell papilloma. Squamous cell carcinoma was the commonest lesion (57%). Its incidence has increased significantly in the last decade. The mean age of presentation was the sixth decade. A personal history of tobacco chewing was given by most of the patients in the retrospective group, while the use of pan masala was found to be maximum in the prospective group. The overall agreement between the clinical and histological diagnosis was 95.36% (740 / 776) and the kappa coefficient of agreement was 0.9256. CONCLUSION Histology along with a detailed clinical workup was found to be a useful, reliable, and accurate diagnostic technique for lesions of the oral cavity. An increase in premalignant lesions in the prospective study, associated with increased pan masala intake is alarming and needs to be taken care of.