In patients with chronic pancreatitis, surgical therapy is indicated for intractable pain. There is no definite opinion about the diameter of the pancreatic duct when deciding the necessity for some forms of surgery. In some patients with a small-caliber duct, ductal decompression is also necessary for the relief of refractory pain. Ultrasound-guided needle puncture provides an easy approach for opening the dilated duct, but in the case of a small-caliber duct, needle puncture alone is insufficient. Insertion of a guide-wire into the duct can secure the ductal cavity, even if the duct is not markedly dilated. Using this technique, with or without intravenous administration of secretin, we have performed longitudinal ductal opening in some patients with chronic pancreatitis. We describe our reliable technique for opening of a small pancreatic duct, and the results we obtained in our series.