This guide explains how to use the MDX language in relation to SAS OLAP. MDX is part of the foundation of the SAS 9.1.3 OLAP Server architecture, and it provides functionality for creating and querying multidimensional structures called cubes. The MDX guide discusses basic MDX concepts, MDX queries and syntax, MDX DDL syntax, SAS functions relevant to MDX, MDX usage examples, and MDX functionality supported by SAS. This documentation is intended for users who build SAS OLAP cubes and related MDX queries.