C-reactive protein is the widely used marker in a clinical practice but also a mediator of the inflammatory process. In the introduction the authors describe the structure and function of the C-reactive protein in relation with inflammatory response to different morbidity stimulations. After this, there have been seen the oscillations of C-reactive protein plasma level of healthy people and in inflammatory, neoplastic and immunological diseases with an explanation of the clinical utilities. The current knowledge about presence of C-reactive protein in a different type of circulatory diseases, in heart failure and arrhythmia has been discussed. The importance of the role of C-reactive protein, especially high-sensivity C-reactive protein, in the prediction of circulatory diseases of the healthy members of the population and the prognostic value of C-reactive protein has been underlined.