Immunotherapy is a growing field of interest in the treatment of malignant diseases, such as colorectal cancer (CRC). The induction or enhancement of T-cell responses against tumor-associated antigens is particularly important in tumor vaccination strategies. Successful immunization relies on an intact immune system. Both chemotherapy and the tumor itself are known to potentially inhibit immune responses. In this study we analyzed T cells directed against antigens of cytomegalovirus (CMV) and influenza virus in 39 HLA-A2-positive CRC patients and 29 HLA-A2-positive healthy donors using the tetramer technology. We found no difference between CRC patients and the healthy control group for either the proportion of samples with detection of virus specific T cells or the magnitude of these specific T cells. Although we cannot draw a firm conclusion on T-cell induction in cancer patients during vaccination therapy, our results show that CRC patients retain their antiviral T cells, suggesting a potential susceptibility to immunotherapy. The quantity of adaptive immunity acquired earlier in life seems not to be affected by the presence of CRC.