&NA;A patient with a hemangiopericytoma of the colon is discussed. This is the second such case reported in the English medical literature. Soon after discovery of the tumor, the patient presented with a colonic intussusception with the tumor serving as the lead point. This was reduced by a hypaque enema, but the intussusception recurred twice more, being reduced again by hypaque enema and finally having to be reduced by colonoscopy. At surgery a left hemicolectomy with primary anastomosis was performed. The microscopic, ultrastructural, and pathologic aspects of hemangiopericytoma are discussed with special attention to lesions of the gastrointestinal tract.