OBJECTIVES: To analyse the effectiveness of a combined procedure of massage and electrotherapy with interferential current in individuals with chronic non-specific low back pain of mechanical aetiology. DESIGN: A single blinded randomized controlled trial. SETTING: Clinical setting. PARTICIPANTS: Sixty-two individuals with chronic non-specific low back pain were randomly assigned to an experimental or control group. For 10 weeks the experimental group underwent treatment comprising 20 sessions (twice a week) of massage with interferential current in the lumbar and dorsal-lumbar area, and the control group received superficial lower back massage (effleurage, superficial pressure and skin rolling). MAIN OUTCOME VARIABLES: Oswestry Disability Index, pain visual analogue scale, Tampa Scale for Kinesiophobia, Roland Morris Disability Questionnaire, McQuade Test, Side Bridge Test, quality of life scores and the range of trunk anteflexion motion, which were all assessed before the treatment and immediately after the last treatment session. RESULTS: The 2 × 2 mixed model ANOVA with repeated measurements showed statistically significant group * time interactions for the visual analogue scale (F = 12.839; P = 0.001), Oswestry Disability Index (F = 5.850; P = 0.019), Roland Morris Disability Questionnaire (F = 8.237; P = 0.006) and quality of life (physical function (F = 16.792; P = 0.001), physical role (F = 14.839; P = 0.001) and body pain (F = 11.247; P = 0.001)). CONCLUSIONS: In individuals with chronic non-specific low back pain, interferential current electro-massage achieved a significantly greater improvement in disability, pain and quality of life in comparison to superficial massage after 20 treatment sessions.