Due to the rapid growth of the Internet and use of e-commerce in the recent years, viral
marketing has drawn the attention of manufacturing and service organizations. However, no
research has been conducted to examine the impact of message appeal and message source
credibility on consumers’ attitude with mediating role of intellectual involvement of consumers and
their risk taking level. The aim of this study was to examine the impact of appeal and message
source credibility on consumers’ attitude with mediating role of consumers’ intellectual
involvement and their risk taking level. The population of this study includes consumers of mobile
phones (Samsung, Sony, Nokia, LG and iPhone) in the Bushehr city (Iran). As the population of the
study is unlimited, 430 questionnaires were distributed using available sampling method, and 391
questionnaires were collected and analyzed. Using structural equation modeling, we analysed the
data through smart PLS software. The results show that the appeal and credibility of the message
source impact the consumer attitudes toward the brand. We also found that the intellectual
involvement of consumers plays the mediating role in the relationship between message appeal and
consumer attitudes toward brands. In the relationship between message source credibility and
customer attitude towards the brand, the level of risk taking of people has no mediating role.