Many case studies and several controlled clinical trials have indicated the effectiveness of hypnotherapy for some medical conditions. However, because of methodological inadequacies hypnotherapy is still criticized for not having strong scientific evidence to support its claims. While randomized placebo-controlled clinical trial is generally accepted as the gold standard study design, creating a credible placebo control for hypnotherapy is a major challenge. This paper recommends "neutral hypnosis" as a credible placebo control for hypnotherapy trials.