After a vital pulpotomy in human permanent teeth, the responses of the remaining pulp tissue under formocresol was studied histologically. The class I cavity was prepared on the teeth and the pulp was amputated. Formocresol was placed over the amputated tissue and the cavity was sealed with zinc phosphate cement and amalgam. The teeth were extracted after 1, and 3 weeks following the operation and were decalcified, sectioned and stained with hematoxylin and losin. Microscopic examination reveals as follows; I. Healing of the pulp at the amputated site did not occur in the pulps treated with formocresol. 2. At one week the pulps were normal except only slight inflammatory reaction. 3. At three weeks, the pulps showed the most serious inflammation, bleeding and necrotic state.