Abstract Background The aim of the study was to investigate a prevalence of sarcopenia in patients with gynecological cancer in accordance with current diagnostic criteria of sarcopenia. Methods A series of 513 patients with gynecological cancer who were intended to newly receive initial or salvage treatment were recruited in a prospective study. Eligible patients were examined with dual energy X-ray absorptiometry and underwent handgrip strength test and the Short Physical Performance Battery before treatment. Sarcopenia was defined as both low skeletal muscle mass (skeletal muscle mass index) and low muscle strength (handgrip strength of <18.0 kg) or both low skeletal muscle mass index and low physical performance (Short Physical Performance Battery score of ≤9). Results A total of 475 patients (92.6%) were completely assessed in this study. Eligible patients’ median age was 60 years (range: 29–89 years). Frequencies of patients with low skeletal muscle mass index, low hand grip strength and low Short Physical Performance Battery were 118 (24.8%), 70 (14.7%) and 80 (16.8%), respectively. Sarcopenia was finally identified in 45 patients (9.5%), which accounted for 38.1% of patients with low skeletal muscle mass index, 64.3% of the patients with low hand grip strength and 56.3% of the patients with low physical performance, respectively. Conclusions The prevalence of sarcopenia of 9.5% in patients with gynecological malignancy who were scheduled to newly receive an initial or a salvage treatment. A large-scale, nation-wide study might be planned to elucidate an accurate prevalence of sarcopenia among gynecologic cancer patients. We first reported the prevalence of sarcopenia stringently confirmed in accordance with the current international standard in patients with gynecological cancer.