BACKGROUND: Severe postoperative pain is a major problem after unilateral and bilateral foot surgery. Continuous regional anaesthesia is often used for unilateral surgery. However, for bilateral surgery, the incidence of complications of continuous bilateral compared with unilateral regional anaesthesia is unknown. OBJECTIVES: To assess the incidence of catheter-related complications of bilateral compared with unilateral continuous regional anaesthesia. DESIGN: A prospective observational study.SETTING: Bellinzona Regional Hospital, a tertiary teaching hospital. PATIENTS: Patients (n = 130) scheduled for elective bilateral or unilateral hallux valgus repair treated with continuous popliteal sciatic nerve block using a continuous infusion of ropivacaine 0.15% at 5 ml h for each popliteal catheter by elastomeric pumps. INTERVENTIONS: The incidence of catheter-related complications, effectiveness, pain levels at rest and with motion, patient satisfaction for the first three postoperative days and the incidence of ambulatory visits or readmissions after discharge were measured. A follow-up for neurological or other complications related to regional anaesthesia was performed 6 to 8 weeks after surgery. MAIN OUTCOME MEASURE: The incidence of catheter-related complications comparing bilateral with unilateral continuous sciatic popliteal nerve block. RESULTS: There were no differences in the incidence of catheter-related complications between the groups. Pain scores at rest and with motion were comparable between the groups. All patients were fit for discharge home 3 days after surgery. Patient satisfaction was similar between the groups. There were no unplanned ambulatory visits or readmissions due to complications in either group. No complications related to regional anaesthesia were reported during the follow-up. CONCLUSION: The complication rate, effectiveness and patient satisfaction of bilateral continuous popliteal sciatic nerve block was comparable with unilateral continuous sciatic popliteal nerve block. The follow-up showed that bilateral continuous sciatic popliteal nerve block does not increase the complication rate. However, an outpatient-based study should confirm these data prior to introduction in the ambulatory setting.