One of the key arguments for mobile agent systems is the flexible usage of groups of agents. However, none of the existing mobile agent systems supports agent groups. In this paper we introduce our model of agent groups in mobile agent environments. Various entities of an agent group are consecutively identified and their roles within an electronic market scenario thoroughly pictured. We argue that with the accurate employment of the provided agent group primitives the system’s flexibility can be significantly enhanced: user applications can, for example, trade performance against fault-tolerance. Keywords agent groups, mobile agent systems, synchronization