Abstract. This paper presents an Emergent Ad hoc Routing Algorithm with QoS provision (EARA-QoS). This ad hoc QoS routing algorithm is based on a swarm intelligence inspired routing infrastructure. In this algorithm, the principle of swarm intelligence is used to evolutionally maintain routing information. The biological concept of stigmergy is applied to reduce the amount of control traffic. This algorithm adopts the cross-layer optimisation concept to use parameters from different layers to determine routing. A lightweight QoS scheme is proposed to provide service-classified traffic control based on the data packet characteristics. The simulation results show that this novel routing algorithm performs well in a variety of network conditions.