The article reviews the clinical significance of measuring acute phase proteins (procalcitonin, C-reactive protein and neopterin) for differential diagnosis between bacterial and viral infections. The results of researches preformed at 1984 to 2014, which measured the levels of C-reactive protein, procalcitonin and neopterin in body biological fluids in infectious and non-infection diseases, are analyzed. Most frequently the clinician encounters a situation when it is necessary to differentiate the bacterial infection from other possible causes of increased body temperature, in particular, from viral infections. In some cases, the diagnosis of bacterial infection is possible only after the results of bacteriology, therefore, laboratory markers of bacterial infection, which would allow differentiating the causes of fever and minimizing the number of cases of unjustified antibiotic use, are actively sought out. Combined measuring of three acute inflammation markers was performed in patients with both infectious and non- infectious diseases. In was revealed that the levels of those blood markers correlate with the inflammation severity. Higher diagnostic value of simultaneous measurement of C-reactive protein, procalcitonin and neopterin, as well as the predictive value of procalcitonin and neopterin in monitoring the course of a number of diseases, was shown. Comprehensive analysis of the concentrations of the studied biomarkers in relation to clinical and microbiological data may help to identify patients at high risk of an unfavorable course of some diseases, allowing timely administration of all necessary treatments.