It has become apparent that Mycobacterium mucogenicum isolates recovered from clinical samples are more diverse than was previously realized and include an increasing number of emerging pathogens, as depicted by multilocus sequence analysis. Most clinically significant cases of those organisms involved catheter-related infections. They are susceptible to most antimicrobial agents, but like other rapidly growing mycobacteria, they are resistant to first-line antituberculous agents. A review of the cases of M. mucogenicum complex infection in the literature is addressed here, as well as two additional cases of the closely related species Mycobacterium aubagnense.