SummaryThe“Belgian TB Multidrug Resistance Working Group”determined in collaboration with 28 laboratories carrying out antibiograms for mycobacteria, the prevalence and incidence of multidrug resistance in Belgium in 1992–1993.During this period, respectively 14 (1.1%) and 17 (1.3%) cases of multidrug resistance (i.e. resistance to at least isoniazid and rifampicin, according to the W.H.O. definition), were detected by these laboratories.Since 9 new cases of multidrug resistance were detected in 1992 and 10 in 1993, the incidence of multidrug resistance in Belgium can be estimated at 0.1 per 100.000 inhabitants.Among these 19 new cases, 2 are confirmed as primary resistance cases.