Pulmonary fibrosis was induced following inoculation of Paracoccidioides brasiliensis conidia intranasally in BALB/c mice. Fibrosis was associated with formation of granulomas, increase in lung hydroxyproline, and sustained increases in tissue tumor necrosis factor-alpha and transforming growth factor-beta. This study suggests a role for these cytokines in generation of pulmonary fibrosis associated with chronic granulomatous infectious diseases.