This paper presents an acoustic study devised to investigate the effects of three presumably distinct prosodic position on the phonetic realisation of Polish front vowels in #CV (that is, following a prosodic boundary and a consonantal onset) and #VC sequences (that is, immediately following a prosodic boundary). The results of the experiment suggest that Polish does not seem to distinguish between utterance-initial and phrase-initial positions, with some contrasts present between these two positions and phrase-medial tokens with respect to F1. No effects of position have been found for F2 or vowel duration. There are also no clear differences on the acoustic realisation of vowels depending on whether or not they are adjacent to the prosodic boundary. These results raise questions about the nature of prosodic structure in Polish as compared to other languages which show more robust effects.