Background. Influence of intravenous administration of glucagon on diameter of pathologicaly dilated common bile duct was investigated in 30 postcholecystectomised patients with or without pathological organic alterations in the distal part of common bile duct. Ultrasound equipments Siemens SL2 and Aloka SSD 720 were used in determination of the common bile duct diameter. Results. In the first group of patients without organic alterations in distal part of common bile duct, glucagon administration caused significant narrowing of common bile duct (p<0.01), while in another group of patients with established organic alterations in distal part of common bile duct significant additional dilatation of common bile duct developed after glucagon administration (p<0.01). Conclusions. Authors concluded that glucagon administration could, besides significant improvement in the quality of ultrasound visualisation, be used as diagnostic test in distinguishing organic and functional dilatations of common bile duct.