Neurofibromatosis type 1 (NF1) is an inherited neurocutaneous disorder associated with a high frequency of cognitive and learning difficulties. Based on discrepancies between IQ and academic achievement, approximately 17% of children with NF1 have been classified as having reading impairments. In this study, the lexical and sublexical reading skills of children with NF1 (n = 30) were examined using the Castles' Word/Non-Word Test (modified version), together with measures of neuropsychological functioning and academic achievement. Twenty children (67%) demonstrated deficits in one or more reading subskills, with 75% of these meeting criteria for phonological dyslexia and 20% classified with mixed dyslexia. These findings indicate that a large proportion of children with NF1 may be characterized by a specific difficulty with the sublexical procedure, suggesting a difficulty employing spelling-to-sound rules to assemble a pronunciation when reading. In line with previous studies, the present findings also suggest that discrepancy-based methods may not be sufficiently sensitive to identify children who experience reading difficulties.