BACKGROUND The high relevance of sarcopenia for the aging societies of most developed nations is emphasized by its recent inclusion in the ICD-10-CM (M62.84). However, diagnosing sarcopenia is a daunting task. Apart from varying definitions, the proper assessment of recognized sarcopenia criteria is time and cost consuming. A short and inexpensive screening tool may thus be welcome for clinicians and others working in the area of gerontology. Recently, a simple questionnaire was provided (SARC-F) that may adequately realize this aim. OBJECTIVE The purpose of this study is to compare established sarcopenia definitions (European Working Group on Sarcopenia in Older People [EWGSOP], Foundation National Institute of Health [FNIH], International Working Group on Sarcopenia [IWGS]) with the SARC-F. Our hypothesis was that the diagnostic overlap between the SARC-F and sarcopenia as determined by these recognized definitions was too low to reliably diagnose sarcopenia. METHODS Seventy-four community-dwelling German men aged 70 years and older with established sarcopenia according to EWGSOP and/or FNIH and/or IWGS were screened with the SARC-F questionnaire. RESULTS Applying the definitions of EWGSOP, IWGS, and FNIH, 66.2, 43.2, and 50% of the cohort were classified sarcopenic, respectively. The SARC-F identified 33.5% of the cohort as sarcopenic. The predictive power of the SARC-F increased when men were classified as sarcopenic according to 2 (57.1%) or all (78.8%) sarcopenia definitions. The diagnostic overlap with the 3 sarcopenia definitions varied between 38.8% (SARC-F-FNIH) and 54.1% (SARC-F-IWGS). In comparison, the overlap of diagnosed sarcopenia ranged from 27.0% (FNIH-IWGS) to 49.0% (IWGS-EWGSOP) among the definitions themselves. Only 12.2% of the men met all 3 sarcopenia definitions. CONCLUSION The diagnostic overlap with respect to sensitivity of the SARC-F and present sarcopenia definitions was at least as high as the range of the diagnostic overlap of these approaches themselves. Thus, although the sensitivity of the SARC-F may be debatable, for want of a better option it seems reasonable to consider the SARC-F as a first simple step within a hierarchical screening procedure. Independently of this procedure, a universally accepted mandatory sarcopenia definition along with comprehensive criteria and fixed cutoff points should be provided promptly.