Deployment of large-scale wireless sensor networks poses a number of new problems not foreseen in previous networking scenarios. One of the main issues to be addressed in such networks is to grant fair and efficient channel access to a large number of network nodes. Although it has been shown that CSMA/CA presents some limitations in this regard, it continues to be the adopted solution for channel access and conflict resolution in various protocols (e.g., IEEE802.15.4). In this paper we introduce a simple, fast and robust collision resolution protocol intended to be used in scenarios with a large number of network nodes. We carried out a performance comparison of the proposed algorithm against CSMA/CA by means computer simulations. Our results give evidence of the improved performance and suitability of our proposal to ensure the scalability of the network.