Multi-regional clinical trials (MRCTs) have become a common practice in recent years. Planned and conducted properly, MRCTs could accelerate the availability of important medical products to patients in need and increase efficiency in clinical development. One of the key issues in MRCTs is assessment of the consistency of treatment effects across regions. Hence, “consistency” needs to be clearly defined. Recently, the Japanese health authority issued a guidance document with one Q&A specifically for assessment of consistency. In addition, there are methods developed to define consistent treatment effect which are proposed for different purposes (e.g., bridging studies); these may potentially apply to MRCTs as well. To address the challenges and fully realize the opportunities that MRCTs present, a PhRMA MRCT Working Group was formed in 2008. Within the working group, a work stream was initiated to tackle the issue of defining consistency of treatment effect across regions. In this presentation, some preliminary work from the work stream will be presented. We will provide a systematic review of definitions that potentially could be used for MRCTs and a case study will be used to illustrate and compare these methods.