Background: The Cochrane Hepato-Biliary Group (CHBG) Controlled Trials Register contained approximately 11,500 references on hepatobiliary randomised and controlled clinical trials in August 2009. Issue 3, 2009 of the Cochrane Library, contained 107 reviews and 92 protocols published by the CHBG. We did not know howmany of the references in the Register were already included in the CHBG reviews and how many remained to be included. Objectives: To find out the approximate number of hepato-biliary trials included in the CHBG reviews and the number of those that remain to be included. Methods: We found the total number of trials and the overall total of the number of references to each of the trials included in the 107 CHBG reviews. From these two figures, we could obtain the average number of trials per review and the average number of references per trial. We also calculated the percentage of overall total number of included references in the published reviews out of the total number of references in the Register. Results: In total, 1106 trials with 2408 references were included in the 107 reviews, i.e., 21% of the references in the CHBG Register. The average number of trials in a CHBG review was 10, and the average number of references per trial was 2. Hence, when the 92 published protocols are developed into reviews, another 16% of the references in the Register could be included. Conclusions: Our rough estimation that about 37% of the references in the CHBG register is utilised by published and ongoing reviews points that the CHBG needs to more than double its production until all collected references are studied in CHBG systematic reviews. The forthcoming study-based register may give more precise estimates of possible reviews remained to be developed and the possible number of references to be included in review updates.