background: down syndrome, phonological awareness, writing and working memory. aim: to evaluate the phonological awareness of brazilian children with down syndrome; to analyze the relationship between the writing hypothesis and the phonological awareness scores of the participants; to compare the performance of children with down syndrome to that of children with typical development according to the phonological awareness: tool for sequential evaluation (phonatse), using the writing hypothesis as a matching criteria; to verify the correlation between the phonological awareness measurements and the phonological working memory. method: a group of eleven children aged between 7 and 14 years (average: 9y10m) was selected for the study. phonological awareness was evaluated using the phonatse. the phonological working memory was evaluated through an instrument developed by the researcher. results: all subjects presented measurable levels of phonological awareness through the phonatse. the phonological awareness scores and the writing hypothesis presented a significant positive association. the performance of children with down syndrome was significantly lower than children with typical development who presented the same writing hypothesis. measurements of phonological awareness and phonological working memory presented significant positive correlations. conclusion: the phonological awareness of brazilian children with down syndrome can be evaluated through the phonatse. syllable awareness improves with literacy, whereas phonemic awareness seems to result from written language learning. the phonological working memory influences the performance of children with down syndrome in phonological awareness tasks.