Summary: This paper deals with temporal aspects in data warehouses and their effects on Online Analytical Processing (OLAP) environments. After sketching the multidimensional data model and demonstrating a conventional OLAP architecture the term Temporal OLAP (TOLAP) is introduced. A TOLAP environment is an extended conventional OLAP environment being able to handle temporal data. We choose a metadata based approach where all temporal information are stored in a repository and no modifications to the data warehouse itself are necessary. Furthermore, we propose coloured tables for the presentation of results at the end user’s client.