PURPOSE: to characterize the performance in phonological awareness, rapid naming, reading and writing in students with developmental dyslexia secondary to mental retardation and good readers. METHOD: 20 students from first to fourth grade of a public school of Marília - SP, both genders, from to 8 to 12-year old took part in this study, divided into GI (10 students with interdisciplinary diagnosis of dyslexia, secondary to mild mental retardation) and GII (10 studentswith good academic development according to gender, age and grade level). The students were submitted to the Phonological Awareness Test, the Test of Reading and Writing and Rapid Automated Naming. RESULTS: there were significant differences regarding the performance of students in the syllabic and phonemic tasks, reading and writing, Rapid Automated Naming, with better performance of the students of GII than GI. CONCLUSION: there was a relationship among the findings of naming speed, oral reading and writing under dictation, which were related with the phonological deficit, cognitive-linguistic characteristic of GI and the interference and the lack of direct instruction of their spelling correspondence in a situation of academic activities for both groups.