OBJECTIVE: Endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) is a highly accurate method to obtain specific diagnosis in various diseases. The optimal method of EUS-guided sampling of material for pathologic diagnosis has not been clearly established. The aim of our study was to compare two different techniques of EUS-guided sampling of solid masses, using either non-suction or suction with a 10-ml syringe. MATERIAL AND METHODS: Patients assessed during a 6-month period were randomized to three passes of EUS-guided sampling with suction (26 patients) or non-suction (26 patients). The samples were characterized for cellularity and bloodiness, with a final cytology diagnosis established blindly. The final diagnosis was reached either by EUS-FNA if malignancy was definite, or by surgery and/or clinical follow-up of a minimum of 6 months in the cases of non-specific benign lesions. RESULTS: EUS-guided fine-needle sampling with suction of solid masses increased the number of pathology slides (17.8+/-7.1 slides for suction as compared with 10.2+/-5.5 for non-suction, p=0.0001), without increasing the overall bloodiness of each sample. Sensitivity and the negative predictive values were higher when suction was applied, as compared to the non-suction group (85.7% as compared with 66.7%, p=0.05). CONCLUSIONS: This prospective randomized study showed that EUS-guided fine-needle sampling of solid masses using suction yields a higher number of slides without increasing bloodiness. Although, the proportion of target cells was relatively similar between the suction and non-suction sampling techniques, the sensitivity and negative predictive values of the procedure were significantly higher when suction was added.