With increasing amount of data being stored in XML format, OLAP queries over these data become important. OLAP queries have been well studied in the relational database systems. However, the evaluation of OLAP queries over XML data is not a trivial extension of the relational solutions, especially when a schema is not available. In this paper, we introduce the IX-cube (Iceberg XML cube) over XML data to tackle the problem. We extend OLAP operations to XML data. We also develop efficient approaches to IX-Cube computation and OLAP query evaluation using IX-cubes.