An advertisement display system, for use with a plurality of existing portable toilets arranged side-to-side with a gap between the toilets, for providing a substantially continuous advertising presentation. The system comprises a plurality of bracket assemblies each of which are selectively vertically attached along a corner of the toilet, and a plurality of substantially rectangular advertising panel assemblies which are selectively inserted between adjacent pairs of the bracket assemblies. The bracket assemblies include a plurality of intermediary bracket assemblies which are selectively mounted to the corners of the intermediary toilets in the series. A projecting portion of the intermediary bracket assembly extends beyond the side of the toilet to which it is attached. Accordingly, the advertising panel inserted into a vertical channel within the projecting portion also extends into the gap, thereby allowing the advertising display system to appear to be a single, continuous advertising panel.