Spinal manipulation is applied in manual therapies such as Osteopathy, Chiropractic and Physical Therapy and is widely used for acute and chronic non-specific low-back pain. There is moderate evidence that spinal manipulation is superior to sham spinal manipulation for improving short-term pain and function in chronic and acute non-specific low back pain. However the therapeutic mechanisms involved in this procedure are not well understood. Furthermore, while the high velocity and low amplitude spinal therapy has been shown to be effective in reducing pain and improving functional capacity in subjects with non-specific low back pain, the effect on postural variables have not been investigated. Therefore, the aim of this study is to evaluate the acute effect of lumbar manipulation on pain and postural variables.