Recently, several approaches and systems were proposed to store in the same database data and the ontologies describing their meanings. We call these databases, ontology-based databases (OBDBs), and Ontology-based data denotes those data that represent ontology individuals (i.e., instance of ontology classes). To ensure a high performance of queries on top of these OBDBs, efficient representation of ontology-based data becomes a new challenge. Two main representation schemes have been proposed for ontology-based data: vertical and binary representations with a variant called hybrid. In all these schemes, each instance is split into a number of tuples. In this paper, we propose a new representation of ontology-based data, called table per class. It consists in associating a table to each ontology class, where all property values of a class instance are represented in a same row. Columns of this table represents those properties of the ontology class that are associated with a value for ...