Objective To investigate the clinicopathological characteristics,treatment methods and prognosis of rectal cancer in patients younger than 40 years old.Methods From Jan,1998 to Dec,2003,325 treated rectal cancer patients with complete surgical records were divided into two groups:young patients group(younger than 40 years old)49 patients,accounted for 15.1%;middle and old patients group(older than 40years old)276 patients,accounted for 84.9%.The clinicopathological characteristics,treatment methods and follow-up data were compared.Results Among the younger patients,cancer in middle and lower segments of rectum accouned for 79.6%(39/49),infiltrative cancer accounted for 55.1%(27/49),mucous and low-differentiated cancer accounted for 83.7%(41/49),cancer invasion of serosa occurred in 87.8%(43/49),lymph node metastasis in 75.5%(37/49),Miles operation was performed in 65.3%(32/49)and Dixon operation in 34.7%(17/49).These characteristics differewed significantly from middle-aged and old patients.And the 5-year survival-rate in youn patient group was 32.7% and in middle and old patient proup was 60.9% respectively,(P