Objective To study comparatively the clinical anaesthetic potency and adverse effects to children of 0.375% ropivacaine used for brachial plexus block in upper-limb paediatric surgery.Methods After undergoing basal anesthesia with ketamine,36 children scheduled for hand and forearm surgery were randomly allocated to receive brachial plexus block with 0.375% ropivacaine(group A) and to receive intravenous anesthesia with ketamine(group B).The effect of sensor block and motor block,the changes of vital sings,the occurrence of side effect(nausea and vomiting) and palinesthesia of children were observed.Results The patients in group A kept a steady vital signs,their blood pressure,cardiac and respiration rate were similar to the backgroud level before anesthesia,whereas in group B the blood pressure,cardiac and respiration rate of patients were increased and kept a rather higer level,fluctuated with the depth of anesthesia.Conclusion Ropivacaine used for brachial plexus block in upper-limb paediatric surgery is a simple,feasible,and safe method with anesthetized perfectly and less complication.