Statistics for A laboratory investigation on the suspended perforated hollow cylinders in a single row was conducted in a two-dimensional wave flume, to study their hydraulic performance. The influence of depth of submergence, size of pipes, percentage of perforations and water depth on wave reflection characteristics have been investigated. From the investigation it was found that, as the relative depth of submergence increases, reflection increases. Water depth has insignificant effect on reflection coefficient K<inf>r</inf>. The reflection coefficient K<inf>r</inf> increases as incident wave steepness increases. For perforated pipes, size of the pipe has negligible effect on K<inf>r</inf>. Wave period alone does not directly influence the reflection. © 1999 Taylor & Francis Group, LLC.