Prospectively the levels of C-reactive protein (CRP) of 40 patients were studied twice within 6-12 hours in case of a suspected infection after different osteosynthetic and orthopedic procedures and compared with the levels of the erythrocyte sedimentation rate (ESR). 16 patients showed an increase of CRP in relation to a wound infection, hematoma or effusion in all but one case. 6 patients showed an increase of ESR, which also could be cleared in all but one case. Those patients with a proved wound infection demonstrated a CRP-rise in 8 cases, a CRP-plateau in 4 cases and no CRP-decrease. The same patients showed an ESR-rise in 3, an ESR-plateau in 7 and an ESR-decrease in even 2 cases. This study indicates that the determination of two CRP-levels with a short interval in case of a clinically suspected infection is another, meaningful criterion in making a decision for an operative revision.