Objective. The conclusion of a systematic review depends on the quality of the individual studies included. This article presents the results of a qualitative comparison using three different methods of quality assessment. Method. A data set of 21 randomised clinical trials (RCTs) from a systematic review concerning the efficacy of laser therapy in patients with musculoskeletal disorders is used. The criteria lists to assess the methodological quality were the 'Maastricht' list, the 'Jadad' list and the 'Delphi' list. Results. The three criteria lists show moderate to good correlation. Major differences between the lists are the number of items, and differences in wording of the items seem to affect the ranking of the studies. Conclusion. Based on our results, we conclude that the Delphi list seems the most practical and satisfactory instrument for quality assessment of RCTs.