Objective:This study was to evaluate the effect of Ropivacaine for the spinal anaesthesia and the quality of analgesia and anaesthesia when clonidine was added.Methods:Spinal anaesthesia was administered to 32 ASA Ⅰ～Ⅱ degree adult patients who were randomly divided into two groups: Ropivacaine group [R=16] and Ropivacaine + Clonidine group .Data collected included;T10 spread time

maximum upper sensory level reached

and onset time and duration of zero power motor blockades

T12 regression time

pain onset time

and sedation score were also recorded.Results:The RC group onset of the T10 spread time was shorter

the maximum upper sensory level reached was higher

the onset time of zero power motor block was faster;The RC group anaesthetic regression time

the duration of zero power motor block

the time of pain onset was longer

and sedation scores was higher.Conclusion:Ropivacaine and ropivacaine combined with clonidine are sufficient to produce good sensory and motor blockade for lower abdomen and lower limb surgery under spinal anaesthesia.Addition of clonidine to Ropivacaine increase the anaesthetic potency by shortening onset time of sensation and motor block

increasing maximum upper sensory block level

prolonging regression time

and prolonging duration of the analgesic period as well as providing some sedation.