A new approach to continuing medical education by distance learning has been implemented. A series of six patient-management problems or challenges were posted to 20 000 doctors throughout Britain. Each doctor had to decide on the diagnosis, investigations, and treatment of the patients described. The challenges covered problems that were important in the doctor's day-to-day work and were designed so that he could obtain immediate feedback about his decisions and compare his own responses with those of a specialist and those of his colleagues. Additional information was available by telephone and by post on request. The series has been well received and is being widely used.