Objective. To evaluate the efficacy and safety of tolpersione injection and oral formulations combined with NSAID over NSAID monotherapy in acute non-specific low back pain. Material and methods. In this randomized double blind study 239 patients were included in the per protocol analysis. The first 5 days of treatment, patients received tolpersione or placebo injection which was followed by per os administration of tolpersione/placebo tablet up to 14 days. NSAID diclofenac tablet was used in both groups through the study. Functionality assessed by the Roland Morris Disability Questionnaire (RMDQ) at day 5 was the primary endpoint. Secondary endpoints were RMDQ at other time points, pain level change at rest and on movement assessed by the Visual Analogue Scale (VAS), the Clinical Global Impression of Improvement/Patient Global Impression of Improvement (CGI-I and PGI-I), change in the range of motion assessed by the distance from the fingertips to the floor, period of disability days, relative (%) changes in the daily dose of diclofenac from the 7th to the 14th day of therapy. Results and conclusion. The primary and secondary endpoints clearly demonstrated the significant superiority of tolpersione added to NSAID monotherapy over NSAID monotherapy. The safety assessment revealed no statistically significant differences between the two groups. Based on the results, tolpersione injection and per os formulations can be considered an effective and safe drugs in the combined therapy for patients with acute nonspecific back pain.