A prospective randomised study. To compare the long-term outcome of anterior cervical decompression and fusion (ACDF) with a cervical intervertebral fusion cage (CIFC) and the Cloward procedure (CP). We have previously shown that the 2 year outcome of ACDF with the CIFC is the same as for the CP. The fusion rate in CIFC group was, however, only 55%, compared to 85% in CP group. The long-term outcome of CIFC is poorly documented. Ninety-five patients with at least 6 months duration of neck pain and radicular arm pain were randomly allocated for ACDF with the CIFC or the CP. Radiographs were obtained at 2 years. Questionnaires about pain, disability (Neck Disability Index, NDI), distress, quality of life and global outcome were obtained from 83 patients (87%) (43 CIFC, 40 CP) at a mean follow-up time of 6 years (range 56-94 months). There were no significant differences in any outcome variable between the two treatments. For both CP and CIFC the pain intensity improved (P<0.0001) whereas the NDI was unchanged at long-term follow-up compared to preoperatively. In the CIFC group patients with a healed fusion had significantly less mean pain (24 mm) and NDI (26%) than patients with pseudarthrosis (42 and 41, respectively). Furthermore, the mean pain and NDI reported by CIFC patients with a healed fusion was significantly less than in healed CP patients (37 and 38, respectively). The long-term outcome is the same for the CIFC and the CP, with similar improvements of pain but with considerable remaining functional disability. However, in the subgroup of patients with healed CIFC the outcome was clearly better than for the non-healed CIFC group, and also clearly better than for the healed CP group. Thus, if the healing problem associated with the CIFC can be solved the results indicate that a better outcome can be expected with the cage than with the CP.