Ageing is inevitably associated with a decline in physiologic reserves. Frailty results from reaching a threshold of decline across multiple organ systems. By consequence, it is associated with a high vulnerability and reduced ability to maintain homeostasis. This vulnerability is not only age-related, but also related to disability and comorbidity, as illustrated by three clinical cases. Sarcopenia, which is defined as age-related loss of muscle mass, is considered to be a central manifestation of frailty. In addition to being highly prevalent in elderly population, frailty also exerts a substantial impact on quality of life. As it is extremely challenging by defying conventional medication and involving new therapeutically approaches, frailty fully qualifies as a new geriatric syndrome.