Three patients with myeloproliferative syndromes (polycythemia vera, myelofibrosis with myeloid metaplasia, and chronic granulocytic leukemia) with coexisting tuberculosis are described. The first patient, with myelofibrosis, was found to have tuberculosis of the spleen. He did not respond to antituberculous therapy. The second patient was found to have miliary tuberculosis. Treatment with antituberculous drugs was lifesaving. After resolution of the tuberculosis, florid chronic granulocytic leukemia appeared. The third patient, with polycythemia vera, developed cervical tuberculous adenitis which responded to isoniazid and streptomycin. Tuberculosis may be a complication of, or a cause of, myeloproliferative disease in some patients.