The sequential use of ^99mTc-methylene diphosphonate(^99mTc-MDP) and ⁶⁷Ga imaging is thought to be useful to diagnose acute hematogenous osteomyelitis, and to determine whether it is active or inactive in chronic osteomyelitis. We compared the results obtained by the sequential use of ^99mTc-MDP and ⁶⁷Ga imaging with those obtained by the surgical culture and biopsy in 31 patients who were supposed to have the osteomyelitis and admitted to Pusan National University Hospital from July 1987 to July 1989. The results were as follows:l. According to the diagnosis at discharge, 4 cases were normal, 20 cases active osteomyelitis, and 7 cases inactive osteomyelitis. 2. Four normal cases were negative both with ^99mTc-MDP and with ⁶⁷Ga. Twenty cases of active osteomyelitis showed positive results both with ^99mTc-MDP and with ⁶⁷Ga. And of 7 cases of inactive osteomyelitis, 6 cases showed positive ^99mTc-MDP and negative ⁶⁷Ga, 1 cases was negative both with ^99mTc-MDP and with ⁶⁷Ga. 3. It is suggested that in active osteomyelitis both ^99mTc-MDP and ⁶⁷Ga were positive, in inactive osteomyelitis ^99mTc-MDP positive and ⁶⁷Ga negative and in normal or wastive ostemyelitis both ^99mTc-MDP and ⁶⁷Ga negative. 4. The sequential use of ^99mTc-MDP and ⁶⁷Ga imaging was particularly useful to diagnose acute hematogenous osteomyelitis in the case of the obscure diagnosis and supposedly normal radiological finding and to determine whether chronic osteomyelitis is active or complicated by an acute flare-up.