Since 2002, the network of the National Reference Center for Mycobacteria and Mycobacterial Resistance to Antituberculosis Drugs has observed an increase in the prevalence of multidrug-resistant Mycobacterium tuberculosis, partly due to the arrival of patients from countries with high tuberculosis endemicity. Multidrug resistance rose from less than 1% before 2002 to 1.3% in 2004. The rates of primary and secondary resistance to at least one first-line antituberculosis drug reported by the AZAY-Mycobacteria network were 5.8% and 15.2% in 2005. These rates are comparable to those in most other Western European countries. (R.A.)