Common inflammatory markers include procalcitonin (PCT) [1], C-reactive protein-to-lymphocyte ratio (CLR) [2], C-reactive protein (CRP), and neutrophil-to-lymphocyte ratio (NLR) [3]. PCT increases after bacterial infection, and the use of antibacterial drugs can be guided by the PCT level [4]. However, the evidence for the use of PCT in guiding antimicrobial efficacy is not very high [4]. Several studies of the performance of PCT in predicting bacteremia have also varied. Many studies [[5], [6], [7]] have shown that CRP is one of the markers of bacterial infection and can be used as a diagnostic indicator of bacteria infection. CRP [5,8] is widely used in the assessment of bacteremia. There is a report showing the diagnostic value of PCT, CRP and NLR in pediatric tumor patients with bacteremia [9]. In recent years, CLR has also been used in the diagnosis of infectious diseases [2,10,11]. At present, PCT, CLR, CRP and NLR are increasingly used in the diagnosis and treatment of patients with bacteremia. The main purpose of this article was to study blood culture specimens, serum specimens (for testing PCT and CRP) and complete blood count specimens collected at the same time point over the past four years to evaluate the prediction of bacteremia in ICU patients by PCT, CLR, CRP and NLR. Similarly, the performance characteristics of PCT, CLR, CRP and NLR were evaluated for their ability to predict bacteremia.