The diffusion of the mobile telecommunication service in a country could be affected by the diffusions of the services in her neighbor countries. Previous studies on the diffusions of the telecommunication service among countries have been mainly focussed on the comparison after individual diffusion estimation. However, it would be natural to think the diffusion of the mobile telecommunication service in one country could affect to and be affected by the diffusion of the mobile telecommunication service in her neighbor country. In this study, we have applied the multinational diffusion model to model the crossnational effect in the diffusion of the mobile communication service in China, Korea, U.S., Japan, and Hong Kong. Among these 5 countries China is the latest country to adopt the mobile communication service, and we were interested in whether the diffusion of the mobile communication service in Korea, U.S., Japan, or Hong Kong has affected the diffusion of the mobile communication service in China or not. In our application result, the diffusion of the mobile communication service in China has been affected significantly by those in all of the 4 neighbor countries.