The cost competitiveness of wave energy must be enhanced if it is to become a viable alternative to fossil fuels. This can be achieved by realising the synergies between wave and offshore wind energy through co-located wind turbines and WECs (Wave Energy Converters). First, by using the infrastructure of the wind farm the WECs will be less costly to install and maintain. Second, by deploying the WECs along the periphery of the farm a milder wave climate (shadow effect) will ensue within the farm and result in. reduced structural loads and enlarged weather windows for Operation & Maintenance. The objective of this work is to investigate the optimum layout for the co-located wind-wave farm with a view to maximising these benefits. This investigation is carried out through a case study: an offshore wind farm consisting of 80 turbines in the Wave Hub area (SW England). To analyse the influence of the firm layout, high-resolution numerical modelling is used, and no fewer than 14 different layouts are compared. We find that the layout does play a fundamental role and that reductions of up to 40% in the significant wave height can be achieved - or up to 64% in terms of energy density. (C) 2015 Elsevier Ltd. All rights reserved.