Abstract Background Endoscopic ultrasound (EUS)-guided fine-needle aspiration (FNA) and fine-needle biopsy (FNB) are the current standard of care for sampling pancreatic and peripancreatic masses. Recently, a 22G EUS-FNB needle with Franseen geometry was developed, and this device was also introduced in a 25G platform. We compared the performance of the 25G and 22G Franseen needles for EUS-guided sampling of pancreatic and peripancreatic solid masses. Methods We conducted a parallel-group randomized non-inferiority trial at a tertiary-care center from November 2018 to May 2019. The primary outcome was the quality of the histologic core assessed using the Gerke score. The optimal histologic core is indicated by a Gerke score of 4 or 5, which enables optimal histologic interpretation. The overall diagnostic accuracy and adverse event rate were also evaluated. Results 140 patients were enrolled and randomized (1:1) to the 25G and 22G groups. Tissue acquisition by EUS-FNB was successful in all patients. The optimal histologic core procurement rate was 87.1 % (61/70) for the 25G needle vs. 97.1 % (68/70) for the 22G; difference −10 % (95 % confidence interval −17.35 % to −2.65 %). High quality specimens were more frequently obtained in the 22G group than in the 25G group (70.0 % [49/70] vs. 28.6 % [20 /70], respectively; P < 0.001). The overall diagnostic accuracy did not differ between the groups (97.4 % for 25G vs. 100 % for 22G). Conclusions The 25G Franseen needle was inferior to the 22G needle in histologic core procurement. Therefore, for cases in which tissue architecture is pivotal for diagnosis, a 22G needle, which procures relatively higher quality specimens than the 25G needle, should be used.