To examine whether LI vowel inventory size could be a contributing factor to the use of temporal cues in L2 vowel perception, this study assessed the perception of English/i-i/by 66 learners of four different Lis: Danish, Portuguese, Catalan and Russian. The L2 learners performed a forced-choice identification task containing natural and duration-manipulated stimuli. Findings suggest that the participants' over-reliance on duration cues seems to be partially related to their LI vowel inventory size. The participants with the largest LI vowel inventory (Danish) demonstrated the most native-like vowel perception and the participants with the smallest LI vowel inventory (Russian) over-relied on duration cues more than the other learners. Interestingly, the participants with somewhat comparable LI vowel inventories (Portuguese and Catalan) performed similarly. Keywords: L2 vowel perception; Vowel inventory size; Cue-weighting.