A long-term follow-up of 263 patients with pulmonary Mycobacterium kansasii infection disclosed seven cases of mycetoma. We report the clinical manifestations of these patients. The incidence was less than that of tuberculosis. All mycetomas originated in large cavity lesions of inactive M kansasii infection. Most patients had received multiple antituberculous antibiotics, including rifampin. Five patients had died, two of underlying disease, one of invasive candidiasis following massive hemoptysis, one of surgical complication, and one of a possible invasive aspergillosis.