It is believed that the mobile agent technology is going to play an important role in future electronic commerce due to the characteristics of mobility and autonomy of the agents, which make it ideal for electronic commerce applications in open network environment. However, a couple of security issues need to be tackled before we can employ mobile agents in real life commercial applications. Some schemes have been proposed to solve the security problems in mobile agent paradigm, such as the undetachable signature scheme, the secure agent scheme using proxy signature and others. Most of the current work, however, mainly focus on the protection of the private key of the customer from the malicious servers, while the other related security issues in electronic commerce, say, privacy protection of the customer, are seldom considered. In this paper, we summarize the security requirements for mobile agent-based electronic transactions and propose a new secure mobile agent scheme for electronic commercial transactions with privacy protection of the customer. With a security analysis, we show that the proposed scheme satisfies all security requirements.