Purpose - This paper examines the performance of UK listed infrastructure over a unique investment period covering the global financial crisis and investigates the significance of UK infrastructure in a multi-asset portfolio. The analysis reveals the level of correlation of UK infrastructure with other major assets classes and substantiates the potential diversification benefits of including UK infrastructure within a mixed asset portfolio. Research Design and Data - The study uses monthly investment return indices obtained from Thomson Reuters DataStream over a ten year period (2001-2010). The paper analysed the UK listed infrastructure investment return characteristics including average annual return, annual risk, Sharpe indices, mean variance portfolio and maximum return portfolio and computes the efficient portfolio frontiers using the risk solver optimization tool. Research Findings - The performance results show that UK infrastructure produced better risk-return trade-offs than those of UK property, private equity, hedge funds and UK stocks over the period 2001-2010. Overall, for the ten year period, UK Water was the best performing asset class outperforming all other asset classes having the highest Sharpe ratio of 0.75. Research Implication - Using the monthly return indices over the ten year period, UK listed infrastructure investment was found to play a consistently significant role in the optimality of mixed-asset portfolios. However, the diversification benefits were more return enhancing than risk reducing, offering investors a platform for matching investment objectives with expectations resulting from a better understanding of the characteristics of UK listed infrastructure investments. Originality - As investors seek better understanding of the performance of infrastructure across the globe, with most previous studies focusing on Australia, US and China, the paper makes significant contribution to the body of knowledge by focusing on UK, a promising investment space for infrastructure industry. Also, given the debate surrounding the emergence of infrastructure as a separate asset class, the paper particularly projects the potential benefits of investing in UK listed infrastructure, offering investors a distinctive platform to launch into a vibrant asset class.