The mesentery is unusual site for plasmacytoma. We have observed a solitary primary mesenteric plasmacytoma with marked nodular deposits of Congophilic amyloid in a 38 year-old man. We believe the present case represents the first case of primary extraosseous mesenteric plasmacytoma in the English literature. The clinical picture, pathologic findings and immuno-histochemical studies are discussed. Autopsy and long-term follow up are needed to determine whether this patient is at risk of developing multiple myeloma, local recurrence, metastatic foci or probable complications related to amyloidosis.