  This paper surveys and organizes research works on medical dialog systems,
which is an important yet challenging task. Although these systems have been
surveyed in the medical community from an application perspective, a systematic
review from a rigorous technical perspective has to date remained noticeably
absent. As a result, an overview of the categories, methods, and evaluation of
medical dialogue systems remain limited and underspecified, hindering the
further improvement of this area. To fill this gap, we investigate an initial
pool of 325 papers from well-known computer science, and natural language
processing conferences and journals, and make an overview. Recently, large
language models have shown strong model capacity on downstream tasks, which
also reshaped medical dialog systems' foundation. Despite the alluring
practical application value, current medical dialogue systems still suffer from
problems. To this end, this paper lists the grand challenges of medical dialog
systems, especially of large language models.
