To evaluate the effectiveness of endoscopic biliary sphincterotomy in patients with a large obstructive stone measuring more than 15mm and in patients with simple stones and to identify the factors influencing endoscopic drainage as well as its complications in the management of large choledochal stones. This is the evaluation of endoscopic retrograde cholangio-pancreatography by a descriptive and analytical retrospective study carried out in the Hepato-Gastro-Enterology II department of the Military Hospital of Rabat between April 2002 and September 2020. 1011 patients included in the study who were divided into two groups: Group I (n = 143): Patients with a large obstructive stone measuring more than 15mm. Group II (n = 868): Patients with one or two stones, or bile duct stones. The overall success rate was 88.7% in group I versus 92.5% in group II (p = 0.125). The overall rate of early complications was 10.5% in group I versus 5.1% in group II (p = 0.017). Only the presence of acute cholangitis and stenosis of the main bile duct were factors associated with decreased overall success of endoscopic treatment. Our study showed that there is no statistically significant difference in the effectiveness of endoscopic treatment in patients with a large stone and those with simple lithiasis. The presence of cholangitis and stenosis of the main bile duct appear to be factors associated with decreased overall success of endoscopic treatment.