Analyzing, structuring and organizing documented knowledge is an important aspect of knowledge management. In order to ease the access to text collections, in literature so-called document maps have been proposed which visualize the inherently vague semantic similarity structure of a corpus of documents. In this paper we investigate a document map system which is specifically designed for typical text access tasks in knowledge management. Based on an empirical task-model we present design, realization and results of a comparative laboratory study which evaluates the document map concept against an alternative text-access interface. We show that the graphical overview offers significant benefits over a text-based access interface for certain knowledge management tasks. We also discuss its drawbacks and point to further system improvements which promise to make the technology even more effective. Categories and Subject Descriptors H.3.3 Information Search and Retrieval (Clustering); H.5...