Spoken word recognition is influenced by words similar to the target word with one phoneme difference (neighbors). In English, words with many neighbors (high neighborhood density) are processed more slowly or less accurately than words with few neighbors. However, little is known about the effects in Mandarin Chinese. The present study examined the effects of neighborhood density and the definition of neighbors in Mandarin Chinese, using an auditory naming task with word sets differing in density levels (high vs. low) and neighbor types (words with neighbors with a nasal final consonant vs. words without such nasal-final neighbors). Results showed an inhibitory effect of high neighborhood density on reaction times and a difference between nasal-final neighbors and vowel-final neighbors. The findings suggest that neighbors compete and inhibit word access in Mandarin Chinese. Yet, other factors at the sublexical level may also play a role in the process.