Background: Cochrane reviews address questions about the effects of health care. Certain specific aspects of the study design and its conduct are therefore to be considered when defining the eligibility criteria for the subjects of a Cochrane review. Both restrictive study design criteria and more liberal design criteria are found in the published Cochrane reviews. The question therefore arises: Do trials with inadequate randomization exaggerate the intervention effects. Objectives: To explore any discrepancies of intervention effects between Cochrane reviews that include studies with liberal criteria only, and the set of reviews that include studies with restrictive criteria only (after the studies with liberal criteria have been removed from the review). Methods: As an illustration, three reviews from the published Cochrane reviews of intervention studies were selected. The included studies in Cochrane review incorporating (i) non-randomized studies, and (ii) randomization without allocation concealment were assessed. Risk of bias and the benefits of intervention effects were comparing with the original results and the results after removal of the included studies with liberal criteria. Results: At the time of writing, this work is still ongoing. However, the differences were brought into focus. Full data will be presented at the colloquium. Conclusion: Excessively broad criteria can raise a concern about discrepancies in the resulting intervention effects. Ways to eliminate such discrepancies are suggested.