Cell-mediated immunity towards tumour antigens (cytosols) of the same histotype and site was evaluated by means of the LMI test in long survivors after surgical resection of adenocarcinoma of the colon, infiltrating ductal carcinoma of the breast, and squamous-cell carcinoma of the lung. A positive migration index (MI less than 85.0) was observed in 17/65 (26.2%) colon survivors, 7/18 (38.9%) breast survivors, and 1/19 (5.3%) lung survivors. 24.5% of all long survivors displayed an immunological memory of the antigen to which they had been exposed.