Reading fluency is one of the basic processes of learning to read. Children begin to develop fluency when they are able to form orthographic representations of words, which provide direct, smooth, and fast reading. Dyslexic children of transparent orthographic systems are mainly characterized by poor reading fluency (Cuetos & Suárez-Coalla 2009; Spinelli, De Luca, Di Filippo, Mancini, Martelli, & Zoccolotti, 2005; Wimmer, 1993). Therefore, the main problem for these children could be the difficulty in developing orthographic representations of the words they read. The aim of this study was to test the ability of dyslexic Spanish-speaking children (whose native language is Spanish) to develop orthographic representations and determine if the context helps them. For this, two experiments were conducted with a group of 100 children, 7-12 years of age. The groups were comprised of 20 dyslexics, 40 chronological age-matched controls and 40 reading level-matched controls. In the first experiment, eight unfamiliar words (four short and four long) were presented six times within the context of a story. In the second experiment, eight pseudowords were presented on a computer and the children had to read them aloud. In both experiments, the reading and articulation times of experimental and control stimuli were compared, before and after the training. Children without dyslexia showed a decrease of the influence of length of word on reading speed, indicating a lexical reading, while for dyslexic children, the influence of length remained unchanged. These results appeared when the stimuli were presented in the context of a story as well as when presented in isolation. In short, our results describe that dyslexic children of transparent orthographic systems have problems in developing orthographic representations of words.