In the present study, 75 patients of breast carcinoma and thirty normal female volunteers were selected. These patients were grouped according to clinical stage. The cell mediated immunity was assessed in term of E-RFC% and humoral immunity was investigated in term of immunoglobulins before and after one month of treatment. RFC% was found to be significantly decreased in untreated patients as compared to normal. After one month of treatment the RFC% showed an increasing trend but remained lower than the normals. In a stage-wide analysis, the RFC% was found to be decreased with the advancing disease. Serum IgG levels were also lower than the normal. After treatment, IgG level was further decreased. The serum IgA was found to be significantly increased as compared to control. However, after treatment the IgA level returned to the normal range. Serum IgM level was unaltered in these patients. When compared with the clinical stage, a progressive decrease in serum IgG and increase in IgA was observed with the advancing stage of the disease. Therefore, the present observation implies that the disturbance in cell mediated and humoral immunity is associated with the malignant process in the tumour bearing host.