CHROMATRA (CHROmatin Mapping Across TRAnscripts) is a visualization tool available as plug-in for the Galaxy platform. It allows detailed yet concise presentations of data derived from ChIP-chip or ChIP-seq experiments by visualizing enrichment scores across genes or other genomic features while accounting for their length and additional characteristics such as gene expression. It integrates into typical analysis workflows and enables rapid graphical assessment and comparison of genome-wide data at a glance.