The results of a study that evaluates the application of hybrid laminar flow control (HLFC) to a long-range, twin-engine subsonic transport aircraft are presented. The study was performed using the Flight Optimization System (FLOPS), a rapid and flexible conceptual design and analysis code. This code is a multidisciplinary system of computer programs for conceptual and preliminary design and evaluation of advanced aircraft concepts.A 300 passenger, twin-engine baseline aircraft was defined for a 6,500 n.mi. design range. All operational and regulatory requirements and constraints, such as fuel reserves, balanced field length and second segment climb are satisfied during the design process. The baseline configuration was sized to account for 50 percent chord laminar flow on the wing upper surface and both surfaces of the horizontal and vertical tails. In addition, the benefits of achieving various amounts of laminar flow on the engine nacelles were also studied. The estimated horsepower extraction, and initial weight and cost increments required for the HLFC system (suction to front spar only) were included in the analysis. Results include comparisons of geometry, weights, fuel burn, cruise lift-to-drag ratio (LVD), and direct operating cost (DOC) for the different configurations. The sensitivity of the results to fuel price and off-design range are also presented.