This research aimed to analyze the influence of the marketing mix on the demand of Thai and foreign tourists along the Mekong Riverside in Nong Khai and Bueng Kan provinces, Thailand that linked to the Lao People's Democratic Republic (Lao PDR), in particular the Vientiane Capital and Bolikhamxay province. Questionnaires were used to collect the data from 410 samples selected by convenience sampling. The data were analyzed via structural equation modeling (SEM) with the WarpPLS 6.0 program. The results showed that the marketing mix comprising product, price, promotion, and process affected the demand of tourists. In consequence, the tourism-related units of Thailand and Lao PDR should focus on a touristic marketing strategy by conserving the standard of the tourist attractions, touristic marketing promotion, and an appropriate price. Moreover, the related stakeholders should become aware of providing services to tourists as means to respond to the demand of Thai and foreign tourists.