This study was conducted to examine the effect of word length on auditory word recognition. Word length can be defined by several sublexical units, such as letters, phonemes, syllables, etc. To find out which sublexical units are influential in auditory word recognition, the auditory lexical decision task was used. In Experiment 1, we examined the partial correlation between the speed of reaction time and the number of sublexical units, and in Experiment 2, we executed ANOVA to find out which sublexical length variable was an influential unit. Through these two experiment, we concluded syllable length was the most important variable on auditory word recognition.