The throat swabs obtained from 1,098 adults and 432 children patients with respiratory diseases were examined for Mycoplasma pneumoniae infection detected by culture and polymerase chain reaction (PCR). Antimicrobial susceptibilities of the resulting 60 M. pneumoniae isolates were evaluated by testing minimum inhibitory concentrations (MICs) of erythromycin, minocycline, tetracycline, josamycin, sparfloxacin, ofloxacin, and ciprofloxacin by a broth micro-dilution method. In a preliminary screening, the detection rate of M. pneumoniae by PCR was 29.2% (277/948) for the adults and 28.3% (90/318) for the children. In the second survey, the isolation rate of M. pneumoniae by culture was 29.3% (44/150) for the adults, and 14.0% (16/114) for the children. The PCR detection rate was 36.7% (55/150) for the adults and 23.7% (27/114) for the children. The $MIC_{90}s$ of the M. pneumoniae isolates were $0.015;{mu}g/ml$ for erythromycin, lower than $0.03;{mu}g/ml$ for josamycin, $0.06;{mu}g/ml$ for sparfloxacin and minocycline, $0.12;{mu}g/ml$ for tetracycline, $0.5;{mu}g/ml$ for ofloxacin and CFC-222, and $1.0;{mu}g/ml$ for ciprofloxacin. The isolates were susceptible to erythromycin, josamycin, sparfloxacin, minocycline, tetracycline, and ofloxacin, but the 63.3% of them was resistant to ciprofloxacin. These results indicate that the PCR method has a significant potential as a rapid and sensitive method for early detection of M. pneumoniae infection in clinical specimens as compared with the culture method, but the PCR method could not provide any information concerning the biological characteristics of M. pneumoniae strains. Erythromycin, josamycin, sparfloxacin, minocycline, and tetracycline could be recommended as the antimicrobial agents of choice in Korea.