OBJECTIVES: The objective of this study was to assess diagnostic efficacy and safety of implantable loop recorder (ILR) in detection of causes of unexplained or/and recurrent syncopes in comparison with conventional diagnostic testing (CDT). METHODS: Comparison was based on a systematic review, carried out according to guidelines published by Medical Services Advisory Committee (MSAC) and the Agency for Health Technology Assessment in Poland. The most important medical databases (MEDLINE, EMBASE, CENTRAL) were searched. Two reviewers independently selected trials, extracted data and assessed their quality (using QUADAS scale). Quantitative analysis was impossible because of heterogeneity between trials with respect to baseline characteristic of participants and meaningful differences in duration of observation periods between ILR and CDT groups. Assessing specificity and sensitivity of ILR was not possible due to lack of reference tests in included studies. Therefore only qualitative analysis was performed. RESULTS: The results of 4 randomized control trial (RCTs) and 32 case series (CSs) were included in the analysis. In 3 RCTs syndromes (syncope and palpitations) were observed in 42-77% of patients in ILR group and 33-73% in CDT group. Determining diagnosis of syncope was successful in 33-73% patients with ILR and in 4-21% patients diagnosed by CDT. The results from 1 RCT indicate that ILR can prevent implantation of pacemaker in 88% patients with unexplained syncope. In CSs syncope and presyncope were reported in 12%-100% patients and ILR enable to obtain diagnosis in 62,5-100% patients. Medical incidents occurred in 2% of patients in CSs. Infections in the insertion site and injuries caused by syncope were most commonly reported. Malfunction of the device occurred in 51 patients in CSs and 1 patient in RCT. CONCLUSIONS: ILR implantation is efficient and safe diagnostic strategy for determine the cause of unexplained or/and recurrent syncope.