In the present experiment we used a semantic judgment task with Arabic words to determine whether semantic priming effects are found in the Arabic language. Moreover, we took advantage of the specificity of the Arabic orthographic system, which is characterized by a shallow (i.e., vowelled words) and a deep orthography (i.e., unvowelled words), to examine the relationship between orthographic and semantic processing. Results showed faster Reaction Times (RTs) for semantically related than unrelated words with no difference between vowelled and unvowelled words. By contrast, Event Related Potentials (ERPs) revealed larger N1 and N2 components to vowelled words than unvowelled words suggesting that visual-orthographic complexity taxes the early word processing stages. Moreover, semantically unrelated Arabic words elicited larger N400 components than related words thereby demonstrating N400 effects in Arabic. Finally, the Arabic N400 effect was not influenced by orthographic depth. The implications of these results for understanding the processing of orthographic, semantic, and morphological structures in Modern Standard Arabic are discussed.