The aim of this study was to describe the pain experience at 1-8 years follow-up of patients who were treated with instrumented fusion because of chronic low back pain, and to evaluate the impact of demographic- and disease-specific variables on pain. The sample comprised 101 of 126 Norwegian patients (response rate 80%), aged 25-60 years (mean 46 years) who were treated in a Swedish hospital between 1993 and 2000. The visual analogue scale and Norwegian Pain Questionnaire were used to evaluate pain. Independent t-tests, anova, correlation and multiple linear regression analyses were performed. Sixteen per cent of patients reported no pain, 17% mild pain, 29% moderate pain and 38% strong to excruciating pain following treatment using instrumented fusion. Demographic- and disease-specific variables explained 29% of the variance in back and hip pain intensities, and 19%, 30%, 6% and 23% of the sensory, affective, evaluative and total pain experience, respectively. Patients who needed to use pain-killing reported more pain than those who did not (p < 0.001). Patients suffering from other chronic conditions also reported more affective pain (p < 0.001). In conclusion, at 1-8 years follow up after instrumented fusion most of the patients suffered from moderate pain or less. Further, amount of pain-killing and comorbidity conditions seemed to be highly related to pain in patients treated with instrumented fusion.