Objective: To explore the clinical effects of unilateral placement of plastic stents by ERCP for nonresectable Bismuth type IV hilar cholangiocarcinoma.
 Methods: A prospective study  was conducted in 42 patients with nonresectable Bismuth type IV hilar cholangiocarcinoma, who had unilateral insertion of plastic stents in the recent 4 years, All of the patients had successful insertion of single plastic stent by ERCP manipulation. Early results (less than 30 days) of procedure-related complications, mortality, long-term results (greater than 30 days)  and survival were observed.
 Results: All of the 42 patients had successful drainage. Mean total bilirubin value decreased from （332.3±163.4）μmol/L to （30.6±18.5）μmol/L, and complete resolution of jaundice was achieved in 61.9% （26/42）of the patients. Early comlications included papilla bleeding due to EST in 4 of 42 patients (9.5%) and acute cholangitis in 10 of 42 patients (23.8%). No procedure-related death occurred. All of the patients needed to have their stents replaced periodically, and the median duration up to the first stent replacement was 65 d, and without significant differences between the two groups in stent insertion to the left and right hepatic duct. Median duration of stent patency was 5.15 months, and median patient survival was 6.5 months,but also no significant differences were found between the two groups.
 Conclusions: Unilateral plastic stent insertion is safe and feasible, can achieve adequate drainage for relatively long time, and can improve life quality and survival for patients with nonresectable hilar cholangiocarcinoma.