In this research, we address the problem of communications lack between heterogeneous multiagent systems. For example, KQML-based agent cannot talk to FIPA-based agent and vice versa. The authors have identified three main reasons why different multiagent systems are not interoperable, which we call ?architectural elements?: (1) inconsistent mental state structures; (2) different syntax and semantics of the agent communication languages; and (3) incompatible message transport mechanisms. To solve this problem, we propose a gateway agent as a translator of the agent communications that assures the integration of heterogeneous multi-agent systems. We have developed a prototype of the gateway agent that can translate messages between KQML agent and FIPA agent. Based on the results, we are studying a higher level of interoperability based on conversation protocols between agents.