Induced mainly by the increased spreading of personal computers in the last few years computer-assisted instruction (CAI) systems for medicine have been developed on a large scale. Proven structure principles are above all the simulation of patient management in a problem-orientated approach, the mathematical simulation of (patho-) physiological functions independent of particular patients and the separation of educational mode and scoring mode. There exists already a large choice in programs dealing with topics of internal medicine--especially cardiology--while operative disciplines are less represented so far. Programs accredited in the US for continuing medical education (CME) are usually of high quality as to medical contents. Other important quality criteria to be mentioned concerning simulation programs are algorithms of medical decision making, completeness and refinement of the medical knowledge base, software design and user interface. CAI is a unique tool to enhance clinical problem solving skills although--of course--it can by no means replace bedside teaching.