In the past, effective surgical adjuvant therapy has been an elusive goal with little or no evidence of benefit from chemotherapy, immunotherapy, or radiation therapy. During the last 2 years, however, randomized trials have produced strong evidence of substantive progress. In colon cancer with regional nodal metastasis, therapy with combined 5-fluorouracil (5-FU) and levamisole has resulted in a 41% reduction in the recurrence rate (P less than 0.00005) and a 33% reduction in the death rate (P = 0.0052). In rectal cancer, combined technique adjuvant therapy using radiation (50.4 Gy) given in combination with 5-FU and preceded and followed by full-dose systemic chemotherapy with a 5-FU-based regimen was evaluated. In comparison with the same dose of radiation used alone, this combined regimen reduced the recurrence rate by 33% (P = 0.0016) and the death rate by 29% (P = 0.025). Of almost equal importance, there was a major reduction in local recurrence from 25% to 13%. Both these regimens would seem sufficiently well established to justify offering them as standard treatment. Of greater potential value to the patient, however, is entry into the currently available clinical trials that are pursuing hopeful avenues of research and offer the prospect of still greater accomplishments in the years to come.