The present study examined whether early exposure in language immersion would result in better pre-attentive discrimination of non-native speech sound contrasts. Mismatch negativity (MMN) responses were measured from two groups of Finnish children. The Monolingual group had no prior exposure to other languages than the native one, while the Immersion group consisted of children attending a French immersion program. The subjects were presented with two vowel contrasts in the oddball paradigm: the first pair was phonemic in the native language and the second was a within category pair in Finnish, but phonological in French. The results revealed that the Monolingual group showed a larger response to the native contrast in comparison with the non-native one, whereas both contrasts elicited a similar response in the Immersion group. These results suggest that early exposure to a new language enhances the pre-attentive discrimination ability reflected in increased MMN amplitude.