OBJECTIVE The aims of this study were to assess the circumstances of diagnosis and accuracy of imaging procedures in patients with cystic pancreatic tumours. METHODS Thirty-five consecutive patients with cystic pancreatic tumours (serous cystadenomas: n = 19, mucinous cystadenomas: n = 9, cystadenocarcinomas: n = 7) were studied from 1988 to 1993. Respective diagnostic values of ultrasonography, endoscopic ultrasonography, CT scan and analysis of cyst fluid were evaluated. RESULTS The circumstances of diagnosis were abdominal pain (74%), weight loss (23%), jaundice (8%), abdominal mass (6%), asymptomatic (6%). Initial diagnosis of cystadenoma was correctly made by ultrasonography, CT scan and endoscopic ultrasonography in 63%, 77% and 84%, and the type of cystadenoma was correctly diagnosed in 20%, 51% and 55%. A pseudocyst was falsely diagnosed in 28%, 12% and 3%, respectively. After blind review of CT scans and endoscopic ultrasonography records, the type of cystadenoma was correctly diagnosed in 82% by both procedures. Cytological examination of cyst fluid of 18 cystic tumours gave correct diagnosis in 10 cases with sufficient material. A low CEA (P < 0.002), Ca 19.9 (P < 0.003) and absence of mucins (P < 0.002) in cyst fluid was evocative of serous cystadenoma. CONCLUSIONS Abdominal pain was the main circumstance of diagnosis in cases of pancreatic cystadenomas. The type of cystadenoma was correctly diagnosed in 82% by CT scan and endoscopic ultrasonography. Cytological examination, tumoural marker and mucin levels in cyst fluid were helpful for an accurate diagnosis of cystic tumours.