Cardiac sarcoidosis is a potentially fatal complication of sarcoidosis. The 1993 guidelines of the Ministry of Health, Labour, and Welfare (MHLW) of Japan have been used as the diagnostic gold standard and for comparison with imaging modalities. (18)F-FDG PET is not currently included in the guidelines. However, studies have shown promising data using (18)F-FDG PET. We conducted a systematic review of studies that evaluated the accuracy of (18)F-FDG PET for the diagnosis of cardiac sarcoidosis compared with MHLW guidelines. Data from a prospective Ontario provincial registry are also reported and included in the metaanalysis. PubMed, Embase, and the Cochrane Central Register of Controlled Trials were searched for studies that satisfied predetermined criteria. Quality evaluation using the Quality Assessment for Diagnostic Accuracy Studies was performed by 2 independent masked observers. Data were extracted and analyzed to measure study-specific and pooled accuracy for (18)F-FDG PET compared with the MHLW as the reference. A total of 519 titles was identified; 7 studies, including the Ontario registry, were selected for inclusion. Metaanalysis of these 7 studies was conducted, with a total of 164 patients, most of whom had been diagnosed with systemic sarcoidosis. The prevalence of cardiac sarcoidosis was 50% in the whole population. Pooled estimates for (18)F-FDG PET yielded 89% sensitivity (95% confidence interval [CI], 79%-96%), 78% specificity (95% CI, 68%-86%), a 4.1 positive likelihood ratio (95% CI, 1.7-10), and a 0.19 negative likelihood ratio (95% CI, 0.1-0.4). The overall diagnostic odds ratio was 25.6 (95% CI, 7.3-89.5), and the area under the summary receiver operator characteristic curve was 93% ± 3.5. The Ontario study yielded sensitivity and specificity of 79% and 70%, respectively. The high diagnostic accuracy determined for (18)F-FDG PET in this metaanalysis suggests potential value for diagnosis of cardiac sarcoidosis compared with the MHLW guidelines. These results may affect patient care by providing supportive evidence for more effective use of (18)F-FDG PET in the diagnosis of cardiac sarcoidosis. Large-scale multicenter studies are required to further evaluate this role.