The microvascularization of the bile duct was studied in 20 adult guinea pigs (Cavia porcellus) using microvascular corrosion casts in the scanning electron microscope. The main supplying and draining vessels are located in the adventitial layer; from there they form the subepithelial capillary network. The micro-angioarchitecture of the common bile duct is reminiscent of that of the cystic and hepatic ducts. The diameter of these ducts is 1,000 µm on average. The micro-vascular arrangement in the bile duct suggests a probable involvement of the capillaries in the absorption of bile hormones