The use of C-reactive protein (CRP) analyses in different fields of clinical practice is increasing each day. In particular, investigations indicating the potency of C-reactive protein as a marker in predicting future coronary heart disease and cerebrovascular disease in healthy people are promising. In parallel with the increasing interest in clinical practice there have been efforts in improving the methods for CRP measurements. Currently, many different methods are available for determining CRP levels. However, it is a very important issue that inconcordance between methods could cause misinterpretitation of CRP results by clinician. When methods are standardized, and pre-analytical and analytical variations are controlled, efficiency of CRP testing will be more increased. In this paper, different aspects of CRP, including its structure, function, clinical relations, lowering serum levels by medical treatment, devolopments in methodology, analytical and pre-analytical variables, are systematically reviewed.