Purpose: Health-related quality of life measures are crucial in assessing the patients with low back pain. Both the Short Form 36 and the EuroQol-5D are valid and reliable instruments for assessing health-related quality of life in patients with musculoskeletal diseases. This study investigated whether or not these two instruments yield equivalent information on the health-related quality of life of patients with chronic low back pain. Materials and methods: One hundred and thirty two patients with chronic low back pain completed both instruments during their enrolment procedure. Results: After controlling for some important socio-demographic variables, the partial correlation coefficients showed that there were generally low to moderate (r<0.49) negative correlation between the dimensions of the two instruments. Factor analysis revealed that although there are some similarities, the two instruments did not provide equivalent information on the health-related quality of life of patients with chronic low back pain. Conclusion: The results of this study indicate that the instruments are not interchangeable for assessing health-related quality of life in these patients.