In 152 in patients of the Aisei-en Leprosarium comparative studies were made on keratinization, degenerative changes, and N/C ratio with those in normal contorols. In addition, leprosy cells were proven on aspirated smear specimens taken from leproma of the face and upper extremity and their N/C ratio was compared with those of normal oral epithelial cells. 1. In leprosy keratinization was less and degenerative change of the exfoliated epithelial cells are higher than in normal. This could be proven histopathologically. 2. These changes did not show a difference between leprosy types. 3. The N/C ratio of exfoiiated epithelial cells showed no difference between normal and leprosy cases. 4. In detection of leprosy cells in aspiration the Ziehl-Neelsen method was highest in its detection percentage, which was followed by hematoxylin-eosion and Papanicolaou technics. 5. In leprosy cells the N/C ratio showed a decrease as the size of the cells showed an increase. 6. The N/C ratio showed a difference between normal epithelial cells and leprosy cells. 7. Papanicolaou technic can be considered a supplementary practical method in detection of leprosy cells in combination with Ziehl-Neelsen's method.