Compliance with the Medical Devices Directive (93/42/EEC) became compulsory for all medical devices placed on the European market in June 1998. Under the directive, manufacturers are required to fulfil a number of requirements leading to the placing of the CE mark on their devices. However, many questions still remain. Not all manufacturers are aware of their responsibilities and not all purchasers are aware of the true meaning of the CE mark. It is vital to understand the purpose of the regulations, the definition of 'medical device', the importance of complying with the manufacturer's intended purpose and instructions, the role of quality systems and clinical investigations in the compliance process, and the decisions which may be made by the manufacturers. It is also important to realise that whilst the directive, if correctly applied and enforced, brings benefits to the medical industry and patients, it is not a substitute for professional judgement in the purchasing process.