Enoxacin (ENX) showed a moderate degree of activities in vitro against Mycobacterium tuberculosis in modified Saunton medium and modified Lowenstein-Jensen Medium with MICs from 1 to 8micrograms/ml. Ofloxacin (OFLX) is superior to ENX, with MICs from 0.5 to 2.0micrograms/ml. In terms of median survival time (ST50), ENX at doses both 3mg (about 150mg/kg) daily and 6mg (about 300mg/kg) intermittently were inactive (P > 0.05) against M. tuberculosis infection in mice. OFLX at the same doses all were very significantly effective (P < 0.01).