The BACTEC system and the Ogawa method were compared for recovery rates anddetection times of mycobacteria from sputum specimens. From the 179 specimens, 78 (43.6%) and 56 (31.3%) isolates were detected with the BACTEC and Ogawa methods, respectively. Of the 78 mycobacterial isolates in the BACTEC method, 53 (67.9%) were M.tuberculosis complex strains, 23 (29.5%) were M. avium complex strains, and others (2strains) (2.6%) were M. kansasii and M. scrofulaceum strains. Of the 56 isolates in the Ogawa method, 37 (66.1%) were M. tuberculosis complex strains, 18 (32.1%) were M. aviumcomplex strains, and 1 (1.8%) was M. kansasii strain. The difference in the recovery ratesbetween the BACTEC (26 M. tuberculosis complex strains, 13 M. avium complex strains) and Ogawa (23 M. tuberculosis complex strains, 12 M. avium complex strains) methodswas not significant in the smear-positive specimens. In the case of smear-negativespecimens, the BACTEC method detected 27 M. tuberculosis complex and 10M. aviumcomplex isolates, on the other hand, the Ogawa method detected 14 and 6 of M. tuberculosiscomplex and M. avium complex, respectively. The mean detection time for M. tuberculosiscomplex was 15 days with the BACTEC method, and 26 days with the Ogawa method. ForM. avium complex, the mean detection times were 5 and 24 days, respectively. These resultsindicate the usefulness of the BACTEC system in the rapid diagnosis of mycobacteria.