The serum soluble interleukin-2 receptor (sIL-2R) was measured in 40 patients with pulmonary tuberculosis by using sandwich enzyme linked immunosorbent assay. The results show that the levels of sIL-2R in sera of the various stage patients are markedly higher than that of the normal controls and the serum levels of sIL-2R were associated significantly with the patients' conditions. These findings suggest that sIL-2R may be an useful referential indicator for diagnosing, monitoring and predicting pulmonary tuberculosis.