From early months of life prosody has a prominent contribution to segmentation: prosodic boundaries overlap with syntactic ones and facilitate the extraction of syntactic regularities both at word and at phrase level. Therefore, the long-term representation of rhythmic features of the native language, especially the stress templates derived from regularities are assumed to play a particular role in pre-lexical processing. We examined the nature of early stress representation in a language with a fixed stress pattern in an electrophysiological experiment (acoustic passive odd-ball paradigm, 10 month-olds: 28 infants; 6 month-olds: 21 infants, 400 items, deviant: p=20%) using bi-syllabic Hungarian pseudo-words to follow how prosodic features contribute to processing saliency and how word stress templates based on regularities may emerge. We used legally and illegally stressed stimulus both in standard and deviant positions in separate conditions. In the legal standard condition two mismatch responses (MMRs) temporally synchronized to each syllable could be recorded. On the contrary, in the illegal standard condition no significant response was found. It seems that language environment influences the processing of speech prosody and the MMR correlates of word stress processing are related both to saliency and to stress templates emerging during the first year of life.