Miniendoscopy of both biliary and pancreatic ducts is thought a valuable diagostic as well as therapeutic tool. However, small caliber endoscopes notoriously suffer from technical shortcomings, uneasiness of use, and limited durability due to minituarization. In the present study, we evaluated the feasability of peroral diagnostic and therapeutic miniendoscopy with a new 7 Fr instrument in an array of hepatobiliary and pancreatic diseases. The flexibel fiberscope (6.000 pixels)has an outer diameter of 8 to 7 Fr (distal tip) with a working length of 1800mm (Polydiagnost, Reichersthausen, Germany). Tip deflection is 90 degree in single-plane. Two working channels (3.6 Fr. and 1.2 FR) accomodate a guide-wire or different interventional accessories (e.g. forceps), and water irrigation. The instrument was passed through the working channel of standard therapeutic side-viewing duodenoscopes. We applied miniendoscopy to 18 patients with different though representative pathology (e.g. chronic pancreatitis, pancreatic cancer, pancreatic cystadenoma, and hepatolithiasis, Mirizzi-syndrome, Klatzkin tumour, sclerosing cholangitis, duodenocystostomy, liver trauma). Endoscopic sphincterotomy was not necessary using the small-caliber 7 Fr instrument. In several patients, therapeutic interventions were performed (e.g. laser lithotripsy of biliary of pancreatic stones, tumour biopsy and brush cytology, guide wire placement). In selected patients, only miniendoscopy yielded the definite diagnosis (e.g. Mirizzi-syndrome). Illumination and image resolution was excellent compared to currently used miniscopes. The instrument performed reliably during the whole study without evidence of damage despite rough handling in certain situations. Image material and further examinations of patients with rare disease will be demonstrated during the DDW meeting. The new 7 Fr cholangio-/pancreatoscope is a feasable and certainly valuable adjunct to the diagnostic and therapeutic armamentarium of the hepatobiliary and pancreatic endoscopist.