Sarcopenia is a complex multifactorial syndrome which could be present in older age (primary sarcopenia) or earlier in chronic disease (secondary sarcopenia). Even if in patients with chronic liver disease an association among sarcopenia and poor clinical outcomes is well known, the data available about the prevalence of sarcopenia in patients with liver cirrhosis, non-alcoholic fatty liver disease and hepatocellular carcinoma are very variable according to the populations in object and, furthermore, few data are available regarding the use of muscular ultrasound to detect this condition. The aim of this study is to define the prevalence of sarcopenia in patients with liver cirrhosis, non-alcoholic fatty liver disease and hepatocellular carcinoma in follow-up at our center and the clinical outcomes associated with this condition, and to determine the reliability of muscular ultrasound to diagnose the condition of sarcopenia through a comparison with other validated techniques such as computed tomography, magnetic resonance imaging and dual-energy X-ray absorptiometry.