Objective To evaluate the effect of renal function on serum procalcitonin in patients with bacterial bloodstream infection (BSI). Methods Patients with double positive blood culture from May 2014 to November 2017 and detected serum procalcitonin(PCT) 12 hours before and after blood culture were analyzed retrospectively. They were grouped according to gram-staining result of pathogens from blood culture and renal function, four groups were gram-positive bacteria with normal renal function group(G⁺/NRF group), gram-positive bacteria with impaired renal function group (including severely impaired) (G⁺/IRF group), gram-negative bacteria with normal renal function group(G^-/NRF group), and gram-negative bacteria with impaired renal function group (including severely impaired) (G^-/IRF group). Levels of PCT among groups were compared, value of PCT level in predicting infection condition of patients with renal impairment and BSI was evaluated by receiver operating characteristic (ROC) curve. Results There were 23 cases in G⁺/NRF group, 27 in G⁺/IRF group (including 11 severely impaired cases), 63 in G^-/NRF group, and 74 in G^-/IRF group (including 23 severely impaired cases). PCT levels between G⁺/NRF group and G⁺/IRF group, as well as G^-/NRF group and G^-/IRF group were neither significantly different (both P>0.05); PCT level in G^-/NRF group was lower than that in severe G^-/IRF group (2.63[0.58-9.28]ng/mL VS 18.23[8.55-49.72] ng/mL, P<0.001). According to PCT break point, endogenous creatinine clearance rate (Ccr) of G^-/NRF group and severe G^-/IRF group was divided into two parts (PCT level>4.26 ng/mL and PCT level ≤ 4.26 ng/mL), ROC curve was drawn, and the area under curve (AUC) was 0.664 (P=0.009). When cutoff for Ccr was 71.81 mL/min, the sensitivity and specificity of positive predictive value of PCT level affected by severe impairment of renal function were 86.0% and 51.2% respectively. Conclusion When patient's renal function is severely impaired and G^- bacteria BSI occurs, the threshold value of PCT level for judging sepsis needs to be further improved than patient with normal renal function (>0.5 ng/mL).