Patients with Dukes A (UICC I) colorectal cancer have a good prognosis after curative resection. It is not known, however, if the outcome is significantly different for UICC Ia and Ib patients or if patients with reduced risks of recurrences can be identified early after surgery. This is of interest, as it would permit a more cost-effective, patient-oriented, and tumor stage-oriented follow-up program. To study these questions, a prospective follow-up database, including 1375 patients after curative resection of colorectal cancer, was analyzed. A total of 296 patients with Dukes A colorectal cancer with a median follow-up of 44 months were studied. Perioperative and follow-up mortality rates were 3% and 14%, respectively. Recurrent disease developed in 10% of Dukes A patients after a disease-free interval of 16 months. Significantly more patients suffering from pT2 (UICC Ib) cancer had recurrent disease than patients with pT1 (UICC Ia) cancer (13% vs. 4%; p <0.05). Preoperative CEA levels in patients with recurrent disease were significantly higher than in long-term disease-free patients (5.3 +/- 1.8 vs. 3.5 +/- 0.6 ng/ml; p <0.05). Curative resection of recurrent disease was achieved in 38% of the patients with recurrences (4% of all patients). Survival analysis showed significantly better survival in patients with Dukes A cancer than in those at higher tumor stages (log rank, <0.0001), and only 39% of all Dukes A patients who died during follow-up had recurrent disease. Dukes A (UICC Ia and Ib) colorectal cancer was diagnosed in 22% of our patients treated for cure, and long-term survival was 86%. There were significantly fewer cases of recurrent disease after curative resection of UICC Ia (pT1N0M0) cancer, so we propose a novel, less intensive follow-up regimen for these patients, leading to a more cost-effective, patient-oriented, and tumor stage-oriented follow-up program.