Even though medical expert systems have been one of
the earliest and prototypical applications of expert system
technology, progress in the field has been disappointingly slow.
Medical expert system developers face a number of difficult
challenges, in part because the process of expert system
development is poorly understood (c.f. developments in software
engineering), resulting in a paucity of applicable process models
and methodologies. In this paper the challenges encountered by
medical expert system developers are conceptualised into a threelayer
model, and strategies devised to overcome the above
challenges are arranged into a software process model suitable
for medical expert system development.