We describe the case of a patient with a chronic pulmonary infection due to a mycobacterium tentatively identified as Mycobacterium flavescens, but finally shown to be Mycobacterium szulgai; this is the first M. szulgai infection reported in Italy. The patient responded to treatment with multiple antituberculosis drugs only after two cycles of 10 and 6 months, respectively. The literature concerning previous case reports in which M. szulgai is involved is revised and the difficulty concerning the identification of this rare mycobacterium, along with its in vitro and in vivo susceptibility, are discussed.