['This study aimed to determine if preoperative time course changes in serum C-reactive protein (CRP) levels can predict clinical outcome of surgical intervention for active infective endocarditis.', 'Surgically treated patients (n = 109) with active infective endocarditis were reviewed retrospectively. We divided the patients into 2 subgroups according to preoperative transition of increasing or decreasing serum CRP levels, and performed a comparative study. The increasing CRP group included 29 patients and the decreasing CRP group included 80 patients.', 'There were more patients with methicillin-resistant Staphylococcus aureus and New York Heart Association functional class IV in the increasing CRP group. Hospital mortality was significantly higher in the increasing CRP group (34.5%) than that in the decreasing CRP group (5.0%) (p <0.05). In multivariate analysis, 3 significant risk factors of surgical outcome were identified: a tendency for increasing preoperative CRP levels (odds ratio [OR]: 18.15, 95% confidence interval [CI]: 1.03-320.78), nosocomial infective endocarditis (OR: 18.73, 95% CI: 1.57-223.60), and dialysis (OR: 1025.46, 95% CI: 2.89-363587.12).'] Does preoperative increasing C-reactive protein affect the outcome for active infective endocarditis?