The deployment of offshore wind farms is hypothesized to have a positive impact on fish communities. Increased habitat heterogeneity enhances species richness and abundance, and benthic fish communities may furthermore benefit from exclusion from trawling activities in wind farm areas. One of the world’s largest offshore wind farms “Horns Rev 1 Offshore Wind Farm” was analysed in a before-after-control-impact sampling design. Sampling included gillnet, grab and acoustics. Results of the studies are analysed and discussed in the report. Overall the study showed that fish communities varied significantly with season but that a distinct horizontal distribution and higher species diversity was found close to the turbines. Reef habitat species not previously recorded in the wind farm area were observed and species diversity increased. Sandeel assemblages typically found in sand bank areas like the Horns Reef were not impacted, although a short term increase in the abundance of greater sandeel was detected due to a temporary increase in juveniles in spring 2004. Cumulative effects of more wind farm development are also discussed in the report.