Mulligan's mobilisation techniques are believed to increase the range of movement (ROM) in patients with low back pain. The primary aim of this study was to investigate the mechanical effects of Mulligan's "SNAG" technique on lumbar flexion ROM. The secondary aim was to measure the intra- and inter-day reliability of lumbar ROM employing the same procedure, and utilising a 3-D motion analysis system for measuring range of motion (ROM).