Background:  The aim of this study was to identify factors that facilitate bilateral insertion of metal stents in malignant hilar stenoses, for which plastic stents often result in incomplete drainage and subsequent cholangitis. Methods:  Between January 1994 and April 1998, we collected 45 cases of advanced (Bismuth stage II or higher) hilar malignant stenoses. The insertion technique was progressively modified and the success rate in the early period (1994 to 1995) was compared with that of a later period (1996) and the most recent period (1997 to 1998). Results:  Overall success rate was 73.3% (33 of 45). The success rates for the three periods were 50%, 67%, and 88% (p = 0.008), respectively. Cholangitis occurred in 3 of the patients with unilateral stents compared with 1 with bilateral stents. Conclusion:  We have described a technique for endoscopic insertion of bilateral metallic stents for malignant hilar stenoses that results in high (>88%) and reproducible success rates.