Two priming experiments examined the separate contribution of lexical tone and segmental information in the processing of spoken words in Mandarin Chinese. Experiment 1 contrasted four types of prime–target pairs: tone-and-segment overlap (ru4-ru4), segment-only overlap (ru3-ru4), tone-only overlap (sha4-ru4) and unrelated (qin1-ru4) in an auditory lexical decision task with 48 native Mandarin listeners. Experiment 2 further investigated the minimal segmental overlap needed to trigger priming when tonal information is present. Four prime–target conditions were contrasted: tone-and-segment overlap (ru4-ru4), only onset segment overlap (re4-ru4), only rime overlap (pu4-ru4) and unrelated (qin1-ru4) in an auditory lexical decision task with 68 native Mandarin listeners. The results showed significant priming effects when both tonal and segmental information overlapped or, although to a lesser extent, when only segmental information overlapped, with no priming found when only tones matched. Moreover, any partial segmental overlap, even with matching tonal cues, resulted in significant inhibition. These data clearly indicate that lexical tones are processed differently from segments, with syllabic structure playing a critical role. These findings are discussed in terms of the overall architecture of the processing system that emerges in Mandarin lexical access.