BACKGROUND: This study aimed to investigate whether the addition of visceral manipulation, to a standard physiotherapy algorithm, improved outcomes in patients with low back pain. METHODS: Sixty-four patients with low back pain who presented for treatment at a private physiotherapy clinic were randomized to one of two groups: standard physiotherapy plus visceral manipulation (n = 32) or standard physiotherapy plus placebo visceral manipulation (n = 32). The primary outcome was pain (measured with the 0-10 Numerical Pain Rating Scale) at 6 weeks. Secondary outcomes were pain at 2 and 52 weeks, disability (measured with the Roland-Morris Disability Questionnaire) at 2, 6 and 52 weeks and function (measured with the Patient-Specific Functional Scale) at 2, 6 and 52 weeks. This trial was registered with the Australia and New Zealand Clinical Trials Registry (ACTRN12611000757910). RESULTS: The addition of visceral manipulation did not affect the primary outcome of pain at 6 weeks (-0.12, 95% CI = -1.45 to 1.21). There were no significant between-group differences for the secondary outcomes of pain at 2 weeks or disability and function at 2, 6 or 52 weeks. The group receiving addition of visceral manipulation had less pain than the placebo group at 52 weeks (mean 1.57, 95% CI = 0.32 to 2.82). Participants were adequately blinded to group status and there were no adverse effects reported in either group. CONCLUSIONS: Our study suggests that visceral manipulation in addition to standard care is not effective in changing short-term outcomes but may produce clinically worthwhile improvements in pain at 1 year.