We have measured the serum levels of soluble CD4, CD8 and IL-2R in 43 patients with AML in complete remission (AML-CR). The sCD8 levels of AML-CR patients (443.9 +/- 224.4 u/ml) were significantly high as compared to that of the normal controls (177.1 +/- 76.3 u/ml), p < 0.01. The sIL-2R levels of AML-CR patients were 715.0 +/- 646.3 u/ml, which significantly differed when compared to 322.1 +/- 65.7 u/ml for the normal controls, p < 0.01. However, the sCD4 levels of AML-CR patients were 9.6 +/- 4.7 u/ml, which did not differ from the 8.3 +/- 2.6 u/ml of the normal controls. The AML-CR patients showed significantly increased sCD8 and sIL-2R levels at all ranges during the remission from one to 188 months. The sCD8 levels and sIL-2R levels of the AML-CR patients showed a close correlation, p < 0.01. Further, the sCD8 levels and lymphokine activated killer cell cytotoxic activity showed a close correlation, p < 0.05. The presence of the activation of anti-tumor immunity may be related to the continuance of the remission in the AML-CR patients.