Objectives: sarcopenia is common especially in hospitalised older populations. The aim of this study was to assess the prevalence of sarcopenia, defined as low skeletal mass and muscle strength, and its impact on 1-year mortality in older patients with cancer. Methods: skeletal muscle mass was estimated using bioelectric impedance analysis and related to height2 (SMI; Janssen et al. 2002). Grip strength was measured with the JAMAR dynamometer and the cut-offs suggested by the European Sarcopenia and 1-year mortality in cancer 413 Downloaded from https://academic.oup.com/ageing/article-abstract/48/3/413/5272750 by Université de Genève user on 26 November 2019 Working Group on Sarcopenia in Older People (EWGSOP) were applied. One-year mortality was assessed by telephone follow-up and the local cancer death registry. Results: of the 439 consecutively recruited cancer patients (60–95 years; 43.5% women), 119 (27.1%) had sarcopenia. Of the patients with sarcopenia, 62 (52.5%) died within 1 year after study entry compared to 108 (35.1%) patients who did not have sarcopenia (P = 0.001). In a stepwise, forward Cox proportional hazards analysis, sarcopenia (HR = 1.53; 95% CI: 1.034–2.250; P < 0.05), advanced disease (HR = 1.87; 95% CI: 1.228–2.847; P < 0.05), number of drugs/day (HR = 1.11; 95% CI: 1.057–1.170; P < 0.001), tumour diagnosis (overall P < 0.05) and Karnofsky index (HR = 0.98, 95% CI: 0.963–0.995; P < 0.05) associated with 1-year mortality risk. The factors sex, age, co-morbidities and involuntary 6-month weight loss ≥5% were insignificant. Conclusions: sarcopenia was present in 27.1% of older patients with cancer and was independently associated with 1-year mortality. The fact that sarcopenia was nearly as predictive for 1-year mortality as an advanced disease stage underlines the importance of preservation of muscle mass and function as a potential target of intervention in older patients with cancer.