MERMAID is a telemedicine project with global reach and a 24-hour, multilingual capability. It aspires to provide a model for the provision of health care services based on the electronic transmission of medical information, via ISDN based videoconferencing. This model is not limited to medical diagnostics but it encompasses all cases where the actual delivery of health care services involves a patient who is not located where the provider is. Its implementation requires the commissioning of an expensive telecommunications infrastructure and the exploration of a number of solutions. In fact, all categories of telemedical applications are considered while the full range of network choices is explored in terms of the cost/performance tradeoffs inherent to them and the developmental stage each of these options occupies in its life cycle. MERMAID utilises advanced land based line transmission technologies to aid the remote patient by making available the specialty care best suited to each particular case. Finally, the development of programme modules for training and education of the seafarers in the use of the MERMAID medical communications system is given top priority as such modules constitute the firmest basis for the promotion of proper practice of telemedicine at sea.