Today, the service sector has been rapidly growing around the world, and providing customers with high level of service quality is among the key factors for achieving business success. However, service processes are usually slow processes which are prone to poor quality, and service quality has the inherent characteristic of heterogeneity. Based on a literature study, it reveals that these issues could be addressed by combining the complementary advantages of Lean and Six Sigma, two latest quality initiatives in the modern quality management field. Therefore, this paper aims at developing and applying a unique Lean Six Sigma methodology in a service quality improvement endeavor. In addition, an empirical case study of patent filing service is utilized to examine the effectiveness of the methodology developed in this research.