We describe the successful postoperative pain management in an Ii-month-old infant who underwent bilateral thoracotomy, using continuous infusions of bupivacaine into two directly placed paravertebral catheters. Haemodynamic parameters and pain scores were measured 1-2h for 60h while the infusions were continued and, intermittently blood samples were taken for subsequent measurement of serum bupivacaine concentrations. The technique provided effective pain relief and the infant required no other analgesia postoperatively. There were no adverse haemodynamic consequences or complications relating to either catheter placement or drug infusions. Serum concentrations of bupivacaine remained below toxic levels throughout the study period, though accumulation did occur.