OBJECTIVES: C-reactive protein (CRP) is one of the markers of inflammation in the body and a predictor of treatment outcome in patients with rheumatoid arthritis (RA) treated with biologic drugs.  CRP levels >10 mg/L are associated with very high cardiovascular risk. The aim of this study was to evaluate the difference in mean CRP levels before and after the initiation of biologic drugs in German rheumatologist practices. METHODS: German Disease Analyzer database including 34 rheumatologist practices was used. Data from 1,695 patients (mean age 52.1 years, 62% female) with a diagnosis of either rheumatoid arthritis (RA, ICD 10: M05, M06) or spondylitis (SP, ICD 10: M45, M46) with an initial biologic drug (etanercept, infliximab, adalimumab, golimumab) prescription (index date) between January 2004 and December 2013 and documented CRP levels within one year pre-index and one year post-index were identified and descriptively analyzed. RESULTS: After the beginning of biologic drug therapy, CRP levels significantly decreased from a mean of 17.7 mg/L before the index date to 11.7 mg/L after the index date (33.9% reduction, P<0.001). In male patients, the relative difference in CRP levels was significantly higher than in female patients (39.0% versus 29.8%). The relative difference decreased with an age (49.5% in the age group <=40 years, 31.4% in age group 41-50, 31.8 in age group 51-60 and 25.9 in age group >60). CONCLUSIONS: In this retrospective database study, performed among 1,695 patients with rheumatoid arthritis or spondylitis, we observed significant reductions in CRP levels associated with male gender and younger age. These data have clinical relevance and significantly extend prior observational studies.