This article has arisen from presentations made at the 4th International Hannover Conference on Hepatic Encephalopathy held in Dresden, 2006. Each author as listed describes their presentation given as part of a section entitled "Therapeutic Studies in Hepatic Encephalopathy." The first section deals with the justification for placebo-controlled trials in hepatic encephalopathy. The other two sections discuss, in detail, outcome parameters for therapeutic studies in the clinical and research setting, respectively.