This paper presents an Arabic morphological analyzer1 that is a component of an architecture which can process unrestricted text from Inter- net. The morphological analyzer uses an object-oriented model to represent the morphological rules for verbs and nouns, a matching algorithm to isolate the affixes and the root of a given word-form, and a linguistic knowledge base consisting in lists of words. The morphological rules fall into two categories: the regular morphological rules of the Arabic grammar and the exception rules that represent the language exceptions. The representation and the implemen- tation of these rules and the matching algorithm are discussed in this paper.