BACKGROUND: Endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) is the preferred modality for the cytological diagnosis of various cancers. Onsite cytopathology interpretation is not available in most centres.OBJECTIVE: To assess whether the the adequacy of tissue sampling assessed by an onsite cytotechnologist improves the diagnostic accuracy of EUS-FNA.METHODS: The present study is a retrospective review of all patients undergoing solid mass EUS-FNA between September 2005 and August 2007. Patients in group I (September 2005 to August 2006) had cytology slides prepared by an endoscopy nurse. Patients in group II (September 2006 to August 2007) had cytology slides prepared, stained and assessed for adequacy of tissue sampling by a cytotechnologist in the endoscopy suite. The final cytopathological diagnosis (definitely positive, definitely negative or inconclusive) was compared between the two groups.RESULTS: A total of 49 EUS-FNA procedures were performed in 47 patients in group I and 60 EUS-FNA procedures in 55 patients in group II. Pancreatic masses were the most common target site in both groups. The total number of needle passes was 105 in group I (mean 2.14 passes per patient; range one to five needle passes) and 158 in group II (mean 2.63 passes per patient; range one to four needle passes). The difference in the number of needle passes was not statistically significant between groups. The final diagnosis was definite in 53% in group I compared with 77% in group II (P=0.01). The percentage of inconclusive diagnoses was 47% in group I and 23% in group II (P=0.001).CONCLUSION: Onsite cytotechnologist interpretation of adequacy of tissue sampling significantly improves the diagnostic yield of EUS-FNA. This appears to be independent of the total number of needle passes undertaken for tissue sampling.