Collagen-vascular diseases are associated with immune dysregulation and inflammation, leading to tissue destruction or compromise. Immunosuppression is more commonly associated with the drugs used to treat these disorders than with the diseases themselves. The newest agents being used to treat collagen-vascular diseases are the tumor necrosis factor (TNF)-alpha inhibitors. U.S. Food and Drug Administration-approved TNF-alpha inhibitors have differing effects on the immune system, reflecting their potency and mechanisms of action. They are particularly effective in breaking down granulomatous inflammation, which makes them effective treatment for sarcoidosis and Wegener's granulomatosis. This same property makes them likely to break down the host defense mechanism that normally contains pathogens such as mycobacteria and fungi in a dormant state, namely the physical and immunologic barrier formed by granulomas in the lung and elsewhere. The most common infection reported with the TNF-alpha inhibitors has been tuberculosis, which may manifest as pulmonary and/or extrapulmonary disease, with the latter being more common and severe than usual. Histoplasma capsulatum, Aspergillus, Cryptococcus neoformans, and Listeria monocytogenes have also been described in a number of cases, and their frequency is discussed.