This paper presents a comparative analysis between the mechanisms of media access control IEEE 802.11 and MMAC-CR (Multichannel MAC protocol for Cognitive Radio) in MANETs (Mobile Ad Hoc Networks). The IEEE 802.11 standard allows the use of multiple channels available at the physical layer, but its MAC protocol is designed for a single channel. However, a MAC protocol of a single channel does not work well in a multichannel environment due to the hidden terminal problem. The simulation results show how the MMAC-CR protocol allows a better use of spectral opportunities thereby increasing the throughput of the MANET network.