Rifampicin (RMP) and two riminophenazine compounds (B663 and B1912) suppressed the growth of Mycobacterium marinumin vitro and in a mouse footpad infection. At appropriate concentrations and dietary dosage, all three drugs showed bactericidal activity in vitro and in vivo. On the basis of minimum inhibitory concentration, RMP was considerably more active than the other two substances in vitro. However, the rate of bactericidal effect was similar for all three drugs. In vivo, the minimum bactericidal dietary dosages of RMP, B663 and B1912 were 0.03, 0.03 and ≤0.01 %, respectively. Results suggest that these drugs may be of value for the treatment of clinical M. marinum infection