Eighty-five patients who had surgery for spondylolisthesis were studied retrospectively both clinically and radiologically to determine if instrumentation lead to better fusion rates and clinical outcome. Degenerative spondylolisthesis accounted for 57 cases and patients who had instrumentation did have a better fusion rate and clinical outcome, with 60% of patients having complete relief from pain. In the group with isthmic spondylolisthesis (28 patients), there was also an improved fusion rate with instrumentation. However, these patient took a longer time before returning to work and had to be protected in a polythene brace. The improved fusion rate radiologically with instrumentation did not translate to better clinical results with regard to pain relief and disability. One patient developed ascending epidural haematoma with instrumentation and resulted in paraplegia. She had incomplete recovery during the follow-up.