Acute bacterial infection of bone and joint presents a real challenge to orthopedist because early diagnosis and treatment are difficult and also essential. In almost all practices, fever and erythrocyte sedimentation rate(ESR) are widely used for monitoring the course, for estimating the effectiveness of treatment, and for the recovery of such illnesses. However, interpreting body temperature is difficult and ESR is nonspecific, is not not sensitive, normalizes slowly. Otherwise, C-reactive protein(CRP) is very sensitive and normalizes fast. CRP, body temperature, and ESR were sequentially measured until a normal value was reached in twenty seven patients in whom acute osteomyelitis (17 patients), acute exacerbation of chronic osteomyelitis(4 patients), and septic arthritis(6 patients) had been diagnosed by positive bacterial culture at Kyungpook National University Hospital from June 1984 to May 1985. The results were as follows: 1. CRP normalized within 8.8 days on average. 2. Fever lasted 4.5 days on average. 3. ESR normalized within 41.6 days on average. 4. Initial mean value of CRP was 4.2 positive in acute in acute osteomyelitis and septic arthritis and 3.5 positive in acute exacerbation of chronic osteomyelitis, therefore CRP can be considered as a very sensitive indicator for early detection of acute bacterial infection of bone and joint. Also sequential CRP determination can be used for monitoring the course, for estimating the effectiveness of treatment, and for the recovery of such illnesses.