A multivariate optimisation code has been modified to represent the application of laminar flow to transport aircraft. This has subsequently been used to obtain optimised configurations for conventional and laminar flow designs. Results are presented, demonstrating the economic benefits of introducing laminar flow technologies to subsonic transport aircraft, with passenger payloads in the 107-517 range. These benefits are seen to improve by a factor of between two and three when the designs are optimised to take maximum advantage of the laminar flow. Sensitivity studies were conducted to investigate the impact of the assumptions used within the project studies on the optimum configurations and operating economics.