Based on the source credibility model and trust transfer theory, this study examined the influence of physician’s personal attributes and word-of-mouth on patients’ medical choice in online healthcare communities, and explored trust transfer from online to offline channel as well as the moderating effect of disease risk on the influence of ability trust and honest trust. Using data from Good Doctor Online, the results revealed that ability trust, benevolence trust, honest trust, and transference trust based on word-of-mouth all had a positive impact on the patients’ medical choice despite slight differences between channels in terms of specific proxies and degree of influence. Disease risk moderated the relationship between ability trust and honest trust and patients’ medical choice. Trust transfer from online channel to offline channel had not been verified.