The current status of adjuvant therapy for colorectal cancer is reviewed using examples from selected, recently completed, randomized, prospective, clinical trials. Although adjuvant systemic therapy is of limited therapeutic efficacy in cancer of the colon, there have been examples of beneficial effects in specific patient subsets. The rationale and current status of adjuvant portal vein hepatic perfusion suggest that it represents a potentially promising approach that must be evaluated in a large prospective randomized study. Finally, the value of adjuvant radiotherapy and chemotherapy for carcinoma of the rectum is assessed. Although one study has demonstrated increased disease-free survival for patients receiving a combination of chemotherapy and radiotherapy, the small numbers in the study preclude any definitive conclusions. The current National Surgical Adjuvant Breast Project, rectal protocol R-01, the largest rectal cancer study with a concomitant "untreated" control, is reviewed and discussed.