 Material and Methods: A randomized clinical trial, double-blinded and placebo-controlled. Patients were selected in the clinics of Federal de University of Sao Paulo UNIFESP according to the following criteria: acute low back pain, both genders, aged between 18 and 65 years, pain between 4 and 8cm in pain numeric scale PNS and who agreed to participate in the study. After signing the informed consent patients were randomly allocated into one of the groups: TENS group TG or Placebo Group PG. In TG was applied conventional TENS with frequency and intensity variation FIV effect, frequency of 100 hertz, a pulse width of 60μs and intensity adjusted according to the individual baseline for each patient without causing muscular contraction. The electrodes were arranged in a cross shape in the paravertebral region levels T12-L1 and L5 - S1. In PG the same procedures were adopted, but did not occur electrical stimulus. Patients were informed that they could or could not feel electric shocks. Treatment consisted of 10 sessions 2x week 5 weeks, with each session lasting 30 . Assessments were made at the following times: T0 baseline, T1 to T10 the beginning and end of each session, T11 after the last session, T30 30 days after the last session and T60 60 days after the last session. Assessment tools: PNS for pain, short-form 36 SF-36, Roland-Morris, self-assessment of improvement Likert scale and drug consumption daily. 