This paper classifies multiagent-based e-commerce into multiagent-based auction, multiagent-based mediation and multiagent-based brokerage and gives a brief survey of related works in each. The paper proposes a framework of CMB, a CBR system for multiagent brokerage, which integrates CBR, intelligent agents and brokerage, in which we also propose a knowledge-based model for CBR. The key insight is that an efficient way for applying CBR in e-commerce is through intelligent agents or multiagent systems, and the work of a human broker should be done by a few intelligent agents in a cooperative way. This approach will facilitate research and development of CBR in multiagent e-commerce.