While Mycobacterium malmoense infections were originally restricted to nort
hern Europe, there has been an increasing number of reports of cases of inf
ection in other countries. Two cases of infections due to Mycobacterium mal
moense in immunocompetent patients in Germany are presented. In both cases
a presumptive diagnosis of tuberculosis was established initially. Mycobact
erium malmoense was cultured after a long incubation period (6-8 weeks). Th
e patients were successfully treated with a triple regimen consisting of ri
fampicin, ethambutol and clarithromycin. The epidemiology and difficulties
in diagnosis of Mycobacterium malmoense infection are discussed.