As the importance of Business-to-Business Electronic Commerce (B2B EC) grows rapidly, integration of EC platform with buyers corporate information systems has become essential. Since many companies adopt the ERP for their information system, ERP solution providers attempt to extend the ERP platform to cover the EC. This approach is called the inside-out approach. On the other hand, the EC solution providers take the outside-in approach through the EC application server. So there is not rigorous standard for the integration of EC with ERP. We propose to adopt the buyers electronic cart, named b-cart which implies the buyers e-cart, approach to handle the conflict. The b-cart means that a buyer owns an e-cart in his/her PC ｏｒ in a third party intermediarys server, in contrast to the currently available suppliers e-cart (namely s-cart). By adopting an open architecture of the b-carts, both sellers and buyers can easily interface their systems according to the standard. This paper evaluate the pros and cons of b-cart approach and various implementation issues.