Measurements have been made of wave height decay in a rough bottomed flume for waves alone and for waves combined with 3 following currents. Tests have also been carried out to quantify energy dissipation at the sidewalls under these conditions. Results show that waves attenuate less rapidly when propagating on a following current, with a corresponding reduction in wave-current friction factor. A simple method is suggested by which wave attenuation in the presence of following and opposing currents can be predicted.