BACKGROUNDTanzania has a high tuberculosis incidence, and genotyping studies of Mycobacterium tuberculosis in the country are necessary in order to improve our understanding of the epidemic. Spoligotyping is a potentially powerful genotyping method due to fast generation of genotyping results, high reproducibility and low operation costs. The recently constructed SpolDB4 database and the model-based program 'Spotclust' can be used to assign isolates to families, subfamilies and variants. The results of a study can thus be analyzed in a global context.RESULTSOne hundred forty-seven pulmonary isolates from consecutive tuberculosis patients in Dar es Salaam were spoligotyped. SpolDB4 and 'Spotclust' were used to assign isolates to families, subfamilies and variants. The CAS (37%), LAM (22%) and EAI (17%) families were the most abundant. Despite the dominance of these three families, diversity was high due to variation within M. tuberculosis families. Of the obtained spoligopatterns, 64% were previously unrecorded.CONCLUSIONSpoligotyping is useful to gain an overall understanding of the local TB epidemic. This study demonstrates that the extensive TB epidemic in Dar es Salaam, Tanzania is caused by a few successful M. tuberculosis families, dominated by the CAS family. Import of strains was a minor problem.