From December 1993 to December 1994, we inserted 14 biliary endoprostheses (Wallstent) endoscopically in 12 consecutive patients (5 men and 7 women; 55-91 years [mean 69.8 years] of age) with malignant biliary stenosis. Successful placement of Wallstent was achieved in all 12 patients. Procedure related death was encountered in one patient (8.3%) who was complicated with emphysematous cholecystitis, combined with a slipping migration of the stent. In 11 of the 12 patients, serum bilirubin levels reduced to less than 2.0 mg/dl. Acute obstruction, which was defined as the obstruction of the stent within 24 hours after the stent placement, occurred in 2 patients (16.7%). Endoscopic nasal bile drainage (ENBD) following stent placement was performed in 4 patients and acute obstruction was not developed in these cases. After endoprosthesis 8 patients were discharged with 6-47 hospital days and the average hospitalized period excluding a case with cerebral infarction was 12.7 days. Excluding one procedure related death, 6 patients died of primary malignancy 39-189 days (average 90.7 days) after endoprosthesis and in 2 cases recurrence of jaundice was observed. The other 4 patients have been alive for 60-174 days (average 102.5 days) without jaundice. The survival rate of the all patients was 64% for 3 months and 32% for 6 months, respectively. In conclusion, we suggested that the endoscopic Wallstent placement would contribute to the improvement of the quality of life for patients with malignant biliary stenosis. However, acute obstruction may be developed in some cases. For the purpose of managing acute obstruction, we recommend ENBD for a few days following the placement of a Wallstent.