This study is aimed to determine the cardiovascular function response to maximal exercise of chronic low back pain patients(N=13) and normal group(N=13). by using BRUCE PROTOCOL, subjects underwent tredmill exercise test. Their cardiovascular function responses during rest and after maximal exercise were compared The responses were analyzed using t-test for SPSS 7.0 program. The Cardiovascular function variables employed at rest time(Vo2, HR. Vo2/kg, VE, Vco2.) and all out time(Vo2peak. HRpeak, Vo2peak/kg, VEpeak. Vco2peak). Result show that : 1 There was no significant difference in Vo2 between chronic low back pain patients and normal group at rest time. However significant difference in Volpeak was observed after maximal exercise( p<.05). 2. There was no significant difference in HR between chronic low back pain patients and normal group at rest time. No significant difference in HRpeak likewise observed. 3. There was no significant difference in Vo2/kg between chronic low back pain patients and normal group at rest time. However significant difference in Vo2peak/kg was observed after maximal exercise load(p<.05). 4. There was no significance in VE between chronic low bark pain patients and normal group at rest time. However significant difference in VEpeak observed after maximal exercise load(p<.05).