The Deoxyribonucleic acid (DNA) content of various epidermal carcinomas recognized clinically as senile Keratosis, In Situ carcinomas, and squamous cell carcinomas, was measured microspectrophotometrically by the two wave length method of Patau. In addition, metaphase and interphase nuclei of a few healing ulcers were measured to serve as controls. The metaphase nuclei were preferred for these measurements mainly because of the lack of any interference due to DNA synthesis at this stage of the cell cycle. The DNA value of the cells in various cases of senile Keratosis always falls in the diploid range. The In Situ carcinomas show a variable degree of mosaic composition ranging from diploid to sixteen ploid, suggesting that there are several aneuploid cell types growing side by side in the same tumor bed. Squamous cell carcinomas, which are invariably invasive, in most cases belong to a hyper-diploid or hyper-tetraploid stem line. The data has been discussed with a view to determine the feasibility of using this technique as a routine method for clinical diagnosis.