Twenty patients with chronic lymphedema had been treated by microwave heating. T-lympocyte subpopulation and HLA-DR phenotype of peripheral blood in patientswith lymphedema were examined by using dual colour flow cytometry before and after treatment. We found that CD4 (T helpe/inducer) in chronic lymphedema decreased significantly (Plt;0.01), HLA-DR increased significantly (P lt;0.05). After the microwave treatment, the CD4, CD4/CD8 ratio increased significantly; HLA-DR, HLA-DR+CD+8 lymphocyte reduced. It was clear that microwave could regulate the immunological disorder of lymphedema patients.