The carcinoma of the vermiform appendix was classified into three types, carcinoid type, cystic type and colonic type by Uihlein and McDonald in 1943. Today they are known as carcinoid, malignant mucocele and adenocarcinoma of the appendix. And there is a tendency to differentiate the adenocarcinoma (colonic type) as primary adenocarcinoma of the appendix from the other two.From 1900 to 1970, twenty-five cases of primary adenocarcinoma of the vermiform appendix, (exclusive of 10 cases of malignant mucocele) have been reported in Japan, our case bringing the total 26. The average age these patients was 55 years old with range of sixteen to seventy-seven years. Seventeen of the cases were males and nine were females. The average age and sex distribution are almost same as those seen in English literature.The patient, a 67 year old, Japanese farmer was diagnosed as acute appendicitis 32 years ago and treated conservatively at that time. Since then he had never had any complaint of abdominal distress before January in 1970, when he felt a distress and noticed a tumor with slight pain at the right lower quadrant. The complaints had continued to his admission in April, 1970. Physical examination, lavoratory findings and X-ray studies suggested the cecal tumor. He was operated in May of this year. The tumor located at the retrocecal region adjacent to the cecum and was 9cm×6 cm×5cm in size. The right hemicolectomy (including about 25 cm of the ileum) and anastomosis between ileum and transverse colon were performed with en-bloc dissection of a part of the psoas major and minor muscles, into which the invasion was suspected. He was discharged in good condition four weeks after the surgery.Histologically, the tumor is moderately differentiated adenocarinoma producing slight amount of mucin. The appendix was almost destroyed but partly recognized at the central part of the tumor. The cecum was invaded into the serosa, muscular layer and partly muscularis mucsae but not into the mucous membrane. No regional lymph node involvement was seen on microscopic examination of the specimen.The anthers added the comment on classification, clinical features, treatment and prognosis of primary adenocarcinoma of the vermiform appendix by reviewing the literature of this subject.