Efficient routing is very important for mobile ad hoc networks (MANETs). Most existing routing protocols consider homogeneous ad hoc networks, in which all nodes are identical, i.e., they have the same communication capabilities and characteristics. Although a homogeneous network model is simple and easy to analyze, it misses important characteristics of many realistic MANETs such as military battlefield networks. In addition, a homogeneous ad hoc network suffers from poor performance limits and scalability. In many ad hoc networks, multiple types of nodes do coexist; and some nodes have larger transmission power, higher transmission data rate, better processing capability, and are more robust against bit errors and congestion than other nodes. Hence, a heterogeneous network model is more realistic and provides many advantages (e.g., leading to more efficient routing protocol design). In this paper, we present a new routing protocol called multiclass (MC) routing, which is specifically designed for heterogeneous MANETs. Moreover, we also design a new medium access control (MAC) protocol for heterogeneous MANETs, which is more efficient than IEEE 802.11b. Extensive simulation results demonstrate that the MC routing has very good performance, and outperforms a popular routing protocol-zone routing protocol, in terms of reliability, scalability, route discovery latency, overhead, as well as packet delay and throughput.