ObjectiveTo investigate the clinical value of serum procalcitonin (PCT) in diagnosis of urinary tract infection(UTI) in elderly patients.Methods114 elderly patients with UTI in the department of infectious diseases of a hospital from January 2013 to December 2014 were analyzed retrospectively, clinical data of patients with abnormal and normal serum PCT were compared, PCT levels in patients with positive and negative blood cultures were compared, PCT receiver operating characteristic (ROC) curve for the diagnosis of bacteremia were drawn.ResultsAmong 114 elderly patients with UTI, 46 were with abnormal PCT, 68 were with normal PCT. In abnormal PCT group, the proportions of patients with highest body temperature within 24 hours of admission, white blood cell count, neutrophil granulocyte percentage, Creactive protein (CRP), blood urea nitrogen（BUN）, creatinine(Cr), and urinary tract obstructive disease were all higher than those with normal PCT (all P<0.05). Among 42 patients with blood culture, PCT level in positive blood culture group(n=12) was higher than negative blood culture group(n=30)(1.93 ［0.57-8.32］ μg/L vs 0.36［0.15-1.01］μg/L, P=0.028）. The area under the ROC curve (AUC) of the patients with bacteremia diagnosed by PCT was 0.72（95%CI：0.54-0.90），at the optimal value of 0.52 g/L, sensitivity, specificity, positive predictive value, and negative predictive value were 83.3%, 63.3%, 47.6%, and 90.5% respectively.ConclusionSerum PCT level can well reflect the severity of elderly patients with UTI, and is of great value in early diagnosis of bacteremia in elderly patients with UTI