Wireless medium is much unreliable compared with the wired medium due to its open nature. The successful transmission rate in wireless environment is much lower than that in wired environments. Background noise, interference from other stations, signal attenuation, signal fading, and Doppler effect will have great impact on the success of a wireless transmission. Consequently, a well designed MAC protocol in wireless environments needs to be aware of the interference in wireless environments. Besides, scarce resources of wireless medium (e.g., bandwidth, battery power, and so on) significantly restrict the progress of wireless networks. Heavy traffic load and high station density are most likely to incur collisions, and further consume bandwidth and energy. The dissertation initially presents an energy-efficient and channel-aware power saving MAC protocol in Wireless Ad Hoc Networks, namely PEM. In PEM, stations are capable of avoiding collisions and saving energy. Besides, PEM takes advantage of power control technique to reduce the interferences among transmission pairs and increase the spatial reuse of wireless networks. Based on the concept of Maximum Independent Set (MIS), a novel heuristic scheme with the aid of interference relationship is also presented in PEM to provide as many simultaneous transmission pairs as possible. Afterward, the dissertation proposes an energy-efficient and channel-aware rate adaptation MAC protocol in Wireless Ad Hoc Networks, namely FaRM. It is well-knows that the channel quality varies with time in wireless environments. Transmission errors may occur due to the variation of channel quality. Accordingly, stations in FaRM can dynamically detect the current SNR to estimate the channel quality through the control frame exchanges. Furthermore, a Finite State Markov Chain (FSMC) is adopted to predict the variation of the channel condition. According to the results generated from FSMC, FaRM enables a station to select an appropriate transmission rate as well as an acceptable fragment length dynamically to transmit in order to both increase the reliability and shorten the channel access time of the transmission. Simulation results shows that the proposed two MAC protocols can utilize the energy well. Besides, the proposed two MAC protocols outperform the existed related works.