We present a histologically proven mucinous adenocarcinoma of the colon in a 40 year old female from Gulu, Northern Uganda. Her elder sister died at 25 years with advanced adenocarcinoma of colon similarly with her mother who died of the same illness 10 years apart. Using the Amsterdam criteria for the diagnosis of the carcinoma of the colon, this is descriptive of Hereditary Non Polyposis Colorectal Carcinoma (HNPCC). Blood examinations revealed microcytic hypochromic anaemia. The Renal and Liver function parameters were essentially normal. The abdominal ultrasonography showed an ill-defined mass in the right hypochondrial region which was heterogeneous with central echogenicity approximately 7.2cm wide and with no intra-abdominal lymphadenopathy or ascitis. At laparotomy, the sonographic findings were confirmed with a demonstrable mass in the hepatic flexure of the colon with hyperemic areas on its serosa. Macroscopically, there was an annular fungating mass with a central necrosis in the hepatic flexure measuring over 7.0cm. Histology of the colonic tumour showed a mucinous adenocarcinoma of the colon (Duke's B). This finding highlights the occurrence of colonic adenocarcinoma in the young person in Northern Uganda, a finding which draws the attention of the medical community towards having a higher index of suspicion for carcinoma of the colon in patients with similar presentation.