In alphabetic languages, the deficit of the phonological awareness is considered as the core deficit in developmental dyslexia. However, the role of phonological awareness in the acquisition of reading Japanese kana, the transparent, mora-based phonogram, has not been understood completely. We examine the abilities of Japanese dyslexic children on different types of Japanese phonological tasks, and discussed which tasks significantly account for each aspect of reading ability. METHODS Fifteen dyslexic children (9.53+/-1.52 years old), and 15 children with normal reading ability (9.17+/-0.90 years old) participated in this study. They performed three types of phonological awareness tasks. The mora counting task and the mora reversal task of words require phonological awareness at the mora level. The letter rhyming task, which resembles the task in English language, requires phonological awareness at the phoneme level. We evaluated the reading ability by the reading speed, the reading errors, and the number of pauses while reading sentences aloud. RESULTS The task performances of the dyslexic group on all three phonological awareness tasks were significantly lower than those of the control group. Stepwise multiple regression analysis revealed that the mora counting task and the rhyming letter task most significantly explained the reading speed and number of reading pauses. The mora reversal task of words, together with the antegraded digit span, significantly explained the reading errors. CONCLUSIONS Japanese dyslexics showed deficits of phonological awareness both at the mora and the phoneme levels. Phonological awareness must be crucial for acquiring the ability of decoding phonograms, including Japanese kana.