Abstract: Cochrane reviewers are occasionally faced with handling large systematic reviews. This is due to the extensive search methods employed by the Cochrane Collaboration when searching for studies for inclusion into reviews. These include searches on various electronic databases, hand searched journals, articles without language restriction, proceedings of meetings and search of bibliographies of published articles. This is further compounded by undertaking a review on a clinical topic where there have been many trials. We undertook a Cochrane review on the clinical effectiveness of different inhaler devices in the treatment of asthma in order to inform clinical practice about the most effective device(s). Some of the problems encountered were multiple device comparisons, multiple endpoints used in trials, multiple variations on study design, drug dose and study duration. A total of 1,208 study abstracts were reviewed for possible inclusion into the review. Full text of 190 papers was obtained, 86 studies were excluded as not suitable and 104 studies were included in the review. These 104 included studies covered 11 inhaler device comparisons (Standard pressurised-metered dose inhaler versus the Autohaler, CFC-free inhaler, Clickhaler, Diskhaler, Easyhaler, Gentlehaler, Multiple dose dry powder inhaler, Rotahaler, Spinhaler, Spiros and the Turbuhaler). Each device comparison presented data in three different ways: absolute change, percentage changed and absolute mean at end of study period. Studies were allocated into one of the following groups: short-term, long-term or cumulative dosing studies. There were four different study designs: crossover, parallel, challenge testing and studies that used different doses. Furthermore, each comparison of inhaler device had from 1 to 13 clinical outcomes. This magnitude of comparisons poses an interesting challenge for RevMan and therefore the reviewer. We discuss the problems and provide some solutions in doing large Cochrane reviews. We illustrate how RevMan can be used to its maximum potential in order to handle large Cochrane reviews. We discuss data extraction and maintenance, appropriate use of weighted mean differences, where it makes sense to use standardised mean differences, where it makes sense to have subtotals and how to develop clinically appropriate subgroups that still makes biological, physiological and statistical sense to combine. We also discuss the difficult choices a Cochrane reviewer has to make in order to remain focused on the clinical objective(s) of the review. The aim of this presentation is to give current and prospective reviewers the encouragement and confidence required to tackle any Cochrane review topic regardless of its size. We hope to achieve this by informing reviewers that 'size does not matter' when it comes to RevMan.