Medical tourism has been raised as the main tourism industry for some countries including Malaysia. Penang has been identified as the leader in Malaysia’s medical tourism market with 60% out of the total international patients’ number is coming from Indonesia. This research aims to know how the government of Penang, Malaysia, sustains this industry to Indonesian patient using the perspective of communication science. With qualitative approach, the data collected by interview and observations to Indonesian patients and family who had the experiences with the medical treatment in Penang Malaysia. Word of mouth (WOM) as a communication behavior is used to sharpen the analysis. The study found that the sustainability of medical tourism among Indonesian patients is strongly coming from WOM among Indonesian people. WOM in this context defines as the dissemination of information and recommendations refers to healthcare services and facilities through personal experiences and referrals among patients. The story of feeling, comfort, satisfaction, service, and the transparency of cost are the elements in the communication process. WOM plays a significant role for the Penang government marketing strategy to Indonesian patients for their medical tourism industry.