The development of metalinguistic awareness, and specifically syntactic awareness, (here measured by age-related changes in the ability to judge and revise unacceptable sentences), reflects developmental changes in focus from semantic to syntactic properties of sentences. Previous research reported that children find judgements of word-order changes easier than morphological violations (Hakes, 1980). We hypothesized that this difference in ease of judgement is linked to the language under investigation. That is, there may be a relationship between the functional load of grammatical morphemes and ability to detect syntactic violations. This study investigated the development of syntactic awareness in Cantonese-speaking children. Fifty-six subjects from four age groups (three, five, seven and 20 years old) were asked to judge the grammaticality of 40 sentences (18 with word-order changes and 22 with morphological violations) and correct the grammatically deviant sentences. There was a significant age effect on subjects’ performance in both judgement and revision tasks. Children scored significantly higher in judging sentences with word order changes than those with morphological violations. They also scored higher on word order revisions than morphological revisions, an unexpected finding. The success of correcting morphological violations varied by morphological marker, apparently according to each marker's degree of obligatory use in the language. It would seem then that syntactic awareness is very much affected by language-specific characteristics.