Little is known about the acquisition of phonology by children with hearing loss who learn languages other than English. In this study, the phonological abilities of 12 Cantonese-speaking children (ages 4:2 to 6:11) with prelingual hearing impairment are described. All but 3 children had almost complete syllable-initial consonant repertoires; all but 2 had complete syllable-final consonant and vowel repertoires; and only 1 child failed to produce all nine tones. Children's perception of single words was assessed using sets of words that included tone, consonant, and semantic distractors. Although the performance of the subjects was not age appropriate, they nevertheless most often chose the target, with most errors observed for the tone distractor. The phonological rules used included those that characterize the speech of younger hearing children acquiring Cantonese (e.g., cluster reduction, stopping, and deaspiration). However, most children also used at least one unusual phonological rule (e.g., frication, addition, initial consonant deletion, and/or backing). These rules are common in the speech of Cantonese-speaking children diagnosed as phonologically disordered. The influence of the ambient language on children's patterns of phonological errors is discussed.