With current and expected developments in unmanned and autonomous systems, LR envisages that within the near future, Unmanned Marine Systems (UMS) will enter into widespread use through many sectors of the maritime industry. Five years ago, we developed the LR Unmanned Marine Systems Code in conjunction with industry to help set out a regulatory framework. It was developed to provide a unique and valuable assurance process to certify the safe design, build and maintenance of UMS to achieve certification which is acceptable to Flag States, local regulators and other parties. LR has applied the code process and framework to a number of UMS projects and is developing a unique understanding of the challenges associated with the technology. Companies involved in producing equipment are often not familiar with marine assurance processes nor the risks and hazards in the marine environment and the rapid development times mean that the equipment may not be appropriate or have the required level of integrity. In this paper, LR will share the experience of applying the Code for UMS.