Systemic inflammation has been linked with the progression of cancer, and, in patients with urological cancers, the presence of a systemic inflammatory response is thought to be indicative of poor prognosis. C-reactive protein (CRP) is an acute-phase reactant, the levels of which can be objectively measured using standardized reliable assays, and a useful marker of systemic inflammation. CRP levels have been shown to predict survival in patients with urological cancers, including renal cell carcinoma, upper urinary tract and bladder cancers, and prostate cancer, and the incorporation of CRP into prognostic models for urological cancers improves the models' predictive accuracy. Furthermore, the kinetics of CRP release and the analysis of dynamic changes in CRP concentrations over time, could predict tumor aggressiveness and potential treatment efficacy. For instance, in long-term survivors of testicular cancer, CRP is associated with the risk of late complications, such as cardiovascular disease, and with the development of second non-germ-cell cancer. CRP could, therefore, be an important biomarker for urological cancers.