The in-vitro activity of sparfloxacin and eight other antimicrobial agents against 64 non-tuberculous mycobacteria (non-MAI) (40 rapidly growing and 24 slowly growing) was compared with those of ciprofloxacin, ofloxacin, amikacin, tobramycin, cefoxitin, imipenem, clarithromycin and doxycycline. Sparfloxacin presented the same activity as ciprofloxacin, being highly active against rapidly growing mycobacteria and showing good in-vitro activity against slowly growing mycobacteria. Amikacin was very active against rapidly growing mycobacteria and clarithromycin presented good activity against all mycobacteria tested. These results suggest that sparfloxacin is a valid agent to be considered in the treatment of Mycobacterium spp. infections.