A clinical retrospective study was conducted. Results of isolated decompression for degenerative lumbar stenosis was compared with the outcome in patients who underwent decompression-stabilisation. From January 1992 to December 2002, 127 patients (average age 65.5) with lumbar degenerative stenosis surgically treated were studied. In all patients the Roy-Camille technique was used for decompression; in 41 patients decompression and posterior stabilisation procedures were carried out. Average follow-up was 6 years (range 2–11 years). The outcomes, evaluated according to Lassale classification, were satisfactory in 81% of the decompressed group while improved to 88% in the stabilised–decompressed group. Three patients of the first group required stabilisation for intractable low back pain (one patient) and lumboradicular symptoms (two patients), while problems related to the device (one hardware failure) and two instances of adjacent segmental instability were seen in the second group. Decompression alone is associated with an increased rate of residual low back pain (one patient in this cohort required fusion). The decompression–stabilisation procedure reduces the incidence of low back pain but is associated with other complications such as significant blood loss, possible wound infections, urinary tract infections (due to increased surgical time), device failures, root impingement and late adjacent segmental pathologies. The Roy Camille technique is effective for achieving adequate decompression. The surgeon should always be aware of patients who might require fusion. The instrumented stabilisation should be reserved for patients with chronic low back pain and evident instability, degenerative spondylolisthesis and spine deformities such as scoliosis or kyphosis.