With development of digital marketing and mobile devices, mobile marketing today is a crucial strategy for enterprises to target customers. However, mobile marketing in Vietnam is still not widespread despite its potentials. Premising on this, our study focuses on examining impact of consumers’ trust and consumers’ attitude towards mobile marketing on the online purchase intention of consumers. An online survey of 210 young consumers in Can Tho city, Vietnam was conducted in 2016 to extend Theory of Reasoned Action (TRA), Technology Acceptance Model (TAM) with additional constructs such as Trust, Entertainment and Irritation. The research finding reveals that Entertainment and Irritation do not have any significant effects on consumers’ attitude and purchase intention. However, consumers’ trust, perceived usefulness and attitude towards mobile marketing are significant predictors of online purchase intention of young consumers in Vietnam. This research offers useful theoretical contribution and managerial implications for companies, marketers, software developers, application developers, practitioners to formulate their communication and electronic marketing strategies related to mobile. The study also extends applicability of TRA and TAM concerning mobile marketing in a developing country.