Purpose To investigate the prevalence of xanthine oxidase (XO) inhibitors prescription at admission and discharge in elderly hospital in-patients, to analyze the appropriateness of their use in relation to evidence-based indications, to evaluate the predictors of inappropriate prescription at discharge and the association with adverse events 3 months after hospital discharge.Methods This cross-sectional study, based upon a prospective registry, was held in 95 Italian internal medicine and geriatric hospital wards. The sample included 4035 patients aged 65 years or older at admission and 3502 at discharge. The prescription of XO inhibitors was considered appropriate in patients with diagnosis of gout, gout nephropathy, uric acid nephrolithiasis, tophi, and chemotherapy-induced hyperurice-mia. In order to evaluate the predictors of inappropriate pre-scription of XO inhibitors, we compared the characteristics of patients considered inappropriately treated with those appro-priately not treated. Results Among the 4035 patients eligible for the analysis, 467 (11.6 %) were treated with allopurinol or febuxostat at hospital admission and 461 (13.2 %) among 3502 patients discharged. At admission, 39 (8.6 %) of patients receiving XO inhibitors and 43 (9.4 %) at discharge were appropriately treated. Among those inappropriately treated, hyperuricemia, polytherapy, chronic renal failure, diabetes, obesity, ischemic cardiomyopathy, heart failure, and cardiac dysrhythmias were associated with greater prescription of XO inhibitors. Pre-scription of XO inhibitors was associated with a higher risk of adverse clinical events in univariate and multivariate analysis.Conclusions Prevalence of inappropriate prescription of XO inhibitors remained almost the same at admission and dis-charge. Inappropriate use of these drugs is principally related to treatment of asymptomatic hyperuricemia and various car-diovascular diseases.