There is a significant increase of the elderly population worldwide, which is accompanied with a rise of the number of people living alone. Moreover, many citizens are at risk due to geographic and social isolation in combination with specific chronic conditions. ICT offers new opportunities in the healthcare area, therefore, within the REMOTE research project, several services have been developed and interconnec (targeted at patients with chronic diseases) available on Symbian OS mobile platforms and computers. This paper presents the Guardian Angel service on the mobile phone, in order to monitor (unobtrusively) the health of the user on the move and alert the medical centre in case of an emergency. The prototype has been evaluated by 30 elderly users and 5 experts, indicating a possible deployment of the application in the healthcare market, but also proposing further improvements for increased usability.