The purpose of this cross-sectional study was to assess the relationships between demographic, clinical and pain variables and health-related quality of life (HRQOL) in patients who had undergone instrumented spinal fusion because of chronic low back pain (CLBP). The sample comprises 101 patients (70% women, mean age 46 years) who had received surgery between 1993 and 2000. The SF-36 Health Survey was used to assess HRQOL. Pain was assessed by sensory, affective and evaluative subgroups of the Norwegian Pain Questionnaire (modified McGill Pain Questionnaire). Age, work status, number of years after surgery, physical training, other chronic conditions and affective and evaluative pain (all p < 0.05) were the most prominent factors affecting HRQOL. The highest adjusted R(2) to explain the variance was physical function (52%) and the lowest was emotional role limitations (15%). Pain, particularly affective and evaluative pain, contributed more to the explained variance of HRQOL than demographic and clinical variables.