Objective To investigate the level and significance of B type natriuretic peptide (BNP), C reactive protein (CRP), white blood cell count (WBC), Lipoprotein a (Lp (a), cholinesterase (ChE) in the elderly patients with pulmonary infection. Methods From January 2010 to December 2017, 79 elderly patients with pulmonary infection were treated in our hospital, according to the severity index of pneumonia (PSI). There were 21 patients in grade I, 35 in grade II to III, and 23 in grade IV to V. The levels of BNP, CRP, WBC, Lp (a) and ChE were detected in the patients. Results BNP, CRP, WBC and LP (a) were higher in grade IV and V patients than in grade I, II and III patients (P?< 0.05), while ChE was lower in grade I, II and III patients (P?