A number of experimental data have shown that naming latency increases with length for pseudo-words but not for frequent real words. Different interpretations have been proposed by current models of reading to account for such a length effect. The aim of the present study was to assess the impact of lexicality on length effect in both the reading and lexical decision tasks. For this purpose, skilled readers were asked to either name or make a lexical decision on words and pseudo-words differing in length from one to three syllables. Skilled readers' results show that length effect is modulated by lexicality in the reading task but no length effect was found in the lexical decision task. The tasks were further proposed to a well-compensated dyslexic participant who exhibited a visual attentional disorder in the absence of any associated phonological problems. A length effect on RTs was found for both words and pseudo-words in lexical decision but naming latencies were affected by length for the pseudo-words only. The present results largely conform to the predictions of the ACV98 model of reading. They are not compatible with the PDP models of reading and can only be partially accounted for by dual route models.