Mycobacterium peregrinum is a rapidly growing mycobacterium that is occasionally associated with disease at different locations. At present, little information is available on antibiotic activity against this microorganism. For this reason, we have carried out a study on the in vitro activity of 15 antibiotics, alone and in combination, against M. peregrinum. Our study shows that the new fluoroquinolones with a C8-methoxy group, especially moxifloxacin, exhibit greater activity against this species. These data should be evaluated in clinical assays or animal models in order to confirm their clinical significance.