Abstract Internet plays an important role in people’s daily life. Internet helps to create E-commerce, which enables people to buy products and services over the network. Although Internet has provided an innovative channel for people to do business, people have different receptivity to it. Prior research has found that factors such trust, security, service quality, online shopping experience and others are factors that influence people to adopt E-commerce. This research set out to consider two factors that are related to E-commerce adoption in Macau. This research hypothesized that trust and willingness to use credit cards for online transactions are positively related to E-commerce adoption. It also hypothesized that trust and willingness to use credit card for online transaction interact to influence adoption. Using data collected from a questionnaire survey, this research found that trust and willingness to use credit card are positively related to intention to adopt E-commerce. The results also support the interaction effect. The nature of interaction is such that trust is related to E-commerce adoption only when willingness to use credit card for online transaction is high. Also, willingness to use credit card for online transaction is related to E-commerce adoption only when the level of trust is high. These results are significant because they add another dimension to our understanding regarding the relationship of trust on E-commerce adoption. The researcher also collected interview data related to Internet users’ adoption of E-commerce. The interview data provided a richer understanding on why Macau people are afraid of using credit card for online transactions and what other E-commerce features they are worried about. The researcher found out more information about interviewees’ credit card usage and habits, their attitudes toward credit card security, and their attitudes toward identity theft over the Internet.