The objective of the thesis was to evaluate the cost reductions and tower design when production costs are included in the design process of an offshore wind turbine tower. First, a tower cost model had to be developed. Then, based on the findings, a cost optimization model was built with the tower design software from Siemens Gamesa Renewable Energy (SGRE). Three scenarios were developed to mimic different supply chains. The results show that the production costs can be reduced by [0.2, 2%]. Moreover, in each scenario, a different optimum tower design was found. Another study into the optimum number of shells per section showed wind turbine manufacturers could reduce production costs up to 20%.