Transcription is one of the basic processes of gene expression, controlled by a complex network of biochemical reactions. Despite its importance, most work on the visualisation of biochemical networks … focuses on the representation of metabolic pathways. The visualisation of the complex networks controlling transcription requires the implementation of a hierarchical approach that allows the display of the structure of each regulatory region with its transcription factors and regulated operons. This paper presents a web-based application for the visualisation of transcriptional control networks. It takes as case study the organism Escherichia coli. The definition of the visual components implemented is mainly based on those proposed by Shen-Orr et al., 2002, slightly extended to visualise complex networks.