Cell-mediated immune response was investigated in fifteen patients with miliary tuberculosis. Delayed hypersensitivity skin test with "recall" antigens PPD and SKSD was positive in two and one patients respectively. An irritant dose of DNCB failed to induce non-specific inflammatory response in the skin of thirteen patients and the same patients also did not develop contact sensitivity to DNCB. Leucocyte migration test in the presence of Mycobacterium tuberculosis was also negative in eight of eleven patients studied. The proportion of E rosette-forming cells was found to be significantly depressed, though the proportion of EAC rosette-forming cells did not show any abnormality. On repeat skin tests in five patients after 3 months of chemotherapy and clinical improvement four showed a positive PPD and DNCB response. It was concluded that there is a marked degree of secondary immunodeficiency in miliary tuberculosis.