The IEEE 802.11 standard specifies a set of transmission rates among which the sender may select the most suitable one based on the channel conditions. Traditionally, the sender increases the data transmission rate upon receiving the various consecutive acknowledgement packets while the data transmission rate is decreased on the absence of acknowledgement packets. This procedure assumes that the channel conditions are the main source of packet transmission errors and losses. However, under medium or high load conditions, transmission impairments are mainly due to collisions. Under these conditions, reducing the data transmission based exclusively on the absence of feedback not only proves ineffective, but it actually degrades the overall networks performance. In this paper, we introduce a novel rate adaptation mechanism capable of mitigating the effect of collisions using the information imbedded in the received packets. Simulation results show that our proposal limits the use of the data transmission adaptation mechanism which in turn results on a significant increase of the aggregated throughput. © 2012 IEEE.