Background Surgery for rotator cuff disease is usually used after non-operative interventions have failed, although our Cochrane Review, first published in 2007, found that there was uncertain clinical benefit following subacromial decompression surgery. Objectives To synthesise the available evidence of the benefits and harms of subacromial decompression surgery compared with placebo, no intervention or non-surgical interventions in people with rotator cuff disease (excluding full thickness rotator cuff tears). Search methods We searched CENTRAL, MEDLINE, Embase, Clinicaltrials.gov and WHO ICRTP registry from 2006 until 22 October 2018, unrestricted by language. Selection criteria We included randomised and quasi-randomised controlled trials (RCTs) of adults with rotator cuff disease (excluding full-thickness tears), that compared subacromial decompression surgery with placebo, no treatment, or any other non-surgical interventions. As it is least prone to bias, subacromial decompression compared with placebo was the primary comparison. Other comparisons were subacromial decompression versus exercises or non-operative treatment. Major outcomes were mean pain scores, shoulder function, quality of life, participant global assessment of success, adverse events and serious adverse events. The primary endpoint for this review was one year. For serious adverse events, we also included data from prospective cohort studies designed to record harms that evaluated subacromial decompression surgery or shoulder arthroscopy.