The effectiveness of the cystic tube (C-tube) and the cystic clip (C-clip) for primary closure of the common bile duct after choledocholithotomy was examined in 10 dogs, followed by an observation period of either 3 months (n = 6) or 1 year (n = 4). No early complications were observed in any of the animals either during or after surgery. The laboratory data were within the normal range during the observation period. No bile leakage or slippage of the C-clip was evident on fistulography from the C-tube in animals examined 5 days after surgery. The tube could be pulled out easily from the cystic duct without any bile leakage or slippage of the clip. A second operation to confirm late complications showed no adhesions around the common bile duct, no bile duct stenosis similar to the Mirizzi syndrome, and no cystic changes of the bile duct or biloma. Our newly designed C-clip for primary closure of the common bile duct after a choledocholithotomy therefore appears to be beneficial and applicable to clinical patients undergoing traditional as well as laparoscopic surgery.