OBJECTIVES: Observational data on the impact of on-site cytopathology evaluation (OCE) during endoscopic ultrasonography-guided fine needle aspiration (EUS-FNA) of pancreatic masses have reported conflicting results. We aimed to compare the diagnostic yield of malignancy and proportion of inadequate specimens between patients undergoing EUS-FNA of pancreatic masses with and without OCE. METHODS: In this multicenter randomized controlled trial, consecutive patients with solid pancreatic mass underwent randomization for EUS-FNA with or without OCE. The number of FNA passes in the OCE+ arm was dictated by the on-site cytopathologist, whereas seven passes were performed in OCE− arm. EUS-FNA protocol was standardized, and slides were reviewed by cytopathologists using standardized criteria for cytologic characteristics and diagnosis. RESULTS: A total of 241 patients (121 OCE+, 120 OCE−) were included. There was no difference between the two groups in diagnostic yield of malignancy (OCE+ 75.2% vs. OCE− 71.6%, P=0.45) and proportion of inadequate specimens (9.8 vs. 13.3%, P=0.31). Procedures in OCE+ group required fewer EUS-FNA passes (median, OCE+ 4 vs. OCE− 7, P<0.0001). There was no significant difference between the two groups with regard to overall procedure time, adverse events, number of repeat procedures, costs (based on baseline cost-minimization analysis), and accuracy (using predefined criteria for final diagnosis of malignancy). There was no difference between the two groups with respect to cytologic characteristics of cellularity, bloodiness, number of cells/slide, and contamination. CONCLUSIONS: Results of this study demonstrated no significant difference in the diagnostic yield of malignancy, proportion of inadequate specimens, and accuracy in patients with pancreatic mass undergoing EUS-FNA with or without OCE.