The volume of information available on the Web is increasing rapidly. The need for systems that can automatically summarize
documents is becoming ever more desirable. For this reason, text summarization has quickly grown into a major research area as
illustrated by the DUC and TAC conference series. Summarization systems for Arabic are however still not as sophisticated and as
reliable as those developed for languages like English. In this paper we discuss two summarization systems for Arabic and report on a large user study performed on these systems. The first system, the Arabic Query-Based Text Summarization System (AQBTSS), uses standard retrieval methods to map a query against a document collection and to create a summary. The second system, the Arabic Concept-Based Text Summarization System (ACBTSS), creates a query-independent document summary. Five groups of users from different ages and educational levels participated in evaluating our systems. Each group had 300 individuals. We also performed a comparative evaluation with a commercial Arabic summarization system.