OBJECTIVES: A side effect of implantable cardioverter defibrillator (ICD) devices is inappropriate shocks. Shocks are painful, can potentially induce lethal arrhythmias and cause severe psychological trauma to cardiac arrhythmic patients. The objective of this study was to investigate the risk of inappropriate shocks in patients who receive ICD therapy. METHODS: A comprehensive literature search was conducted to identify studies describing ICD therapy and reporting inappropriate shock data. The analysis included studies of patients with implantation performed after 2002, having a minimum study population of 50 participants and a minimum 12 month follow up period. The database search was augmented by hand searching references of contemporary systematic reviews in the area of ICD therapy, to ensure all relevant studies were captured. Patient numbers from the identified studies were pooled and summary statistics were estimated. RESULTS: A total of 415 published articles were identified via the database search. Following abstract and full text review, 32 studies were included for data extraction and statistical analysis. A further 4 studies were included from the systematic review hand search. The 36 studies provided a combined total of 807 patients. 16.2% (SD: 11.1) of patients experienced at least one inappropriate shock, this was reduced to 15.3% with exclusion of paediatric studies. The median duration of follow up was 2.6 years. The average number of inappropriate shocks per year for all patients is 0.4 (SD: 0.4). The frequency of inappropriate shocks amongst patients who experienced at least one inappropriate shock is 2.2 (SD: 1.7) per year. In 11 studies that present detailed information on the nature of shocks 32.9% (SD: 22.9) of total shock events were recorded as inappropriate. CONCLUSIONS: A high proportion of patients in recent trials experienced inappropriate shocks. Future development of ICD therapy should focus on the reduction of the inappropriate shock risk.