This paper focuses on the relation between word prosodic structure and vowel duration in Dutch, to the exclusion of phrase-final lengthening and accentual lengthening. Measurements of vowel durations in reiterant speech showed that main stress, secondary stress, and right/left-edge position determine vowel duration. In addition, the experiments made it clear that the durational differences between long and short vowels only surface in syllables with (main or secondary) stress. The observations were summarized in rules which were implemented in a diphone-based Text-To-Speech system (KUN-TTS). The resulting durations showed high correlations with vowel durations measured both in reiterant and lexical words. (C) 2003 Elsevier Ltd. All rights reserved.