According to several reports, the risk of active tuberculosis in patients who are latently infected with Mycobacterium tuberculosis is increased after treatment with tumour necrosis factor alpha (TNF)-blocking agents. These drugs have demonstrated effectiveness and are increasingly being used for treatment of several inflammatory diseases, including rheumatoid arthritis and Crohn's disease. Specialists prescribing TNF-blocking agents should be aware of the risk of tuberculosis and other infections, the unusual and severe clinical presentations and the available preventive measures. In this review, we will weigh currently available data on the risk of infection with intracellular pathogens and in particular tuberculosis in patients treated with TNF-blocking agents, discuss the role of TNF in the pathogenesis of tuberculosis and describe the risk profile of this complication. Awaiting further consensus protocols, a provisional flow chart is presented that is based on dinical parameters to provide a logical framework to reduce and minimise the risk of tuberculosis during TNF blockade.