Many banks worldwide are making substantial investments to offer access to banking services through mobile devices. However, due in part to customers’ concerns about security and trust issues, the adoption rate of mobile banking (MB) has been lower than banks have expected. Disclosure of MB security on banks’ websites can be one way to minimize customers’ risk perception and improve trust in this technology. Nevertheless, there are no studies that investigate how information about MB security disclosed on bank websites affects trust in MB. In order to fill this gap, the main objective of this paper is to analyze the relationship between disclosure of MB security on bank websites and trust in MB, under conditions of information asymmetry. In addition, we also examined how other factors such as perceived risk, personal innovativeness, social influence, age, and gender affect trust in MB. The sample of the study comprised 307 Brazilian undergraduate students. Confirmatory Factor Analysis and Structural Equation Modeling were used to analyze the research model. The main results show that disclosure of MB security on bank websites has a positive relationship with trust in MB, but this relationship is significant only for the respondents that have already visited the website of their banks to get information about MB security. We also observed that the relationship between trust and perceived risk is less significant for students who have already consulted the website of their banks, in comparison with students who have not consulted the website. Theoretical and practical implications of these results are presented in the paper.