Fifty-three patients with colorectal cancer Dukes' B2 and C were randomized after surgery. One group was treated by radio-and/or chemotherapy and the second by radio-and/or chemotherapy and MER. After 24 and 36 months a significant longer disease free interval, lower recurrence rate and better survival was found in the group treated by radio-chemo- and immunotherapy. Treatment was well tolerated and there were few local side effects from the MER injections. The long time efficacy of this adjuvant treatment whether it increases the cure rate or only delays recurrence does require longer follow-up.