Until recently, Medical Affairs as a functional area was relatively under-developed among pharmaceutical companies operating throughout the Asia-Pacific (APAC) region and was often referred to as Medical Marketing. However, there has been an evolution of the function in many advanced markets, and reliance on medical science liaisons (MSLs), which is a main division of Medical Affairs, is growing quickly in Japan where the number of MSLs increased by 23% in 2017-18. This is happening in response to transformative change in the life sciences industry globally, as the era of blockbuster drugs comes to an end. New drugs are now being targeted at niche and rare diseases where the unmet needs are high and the medical science is often both ground-breaking and complex. Treatment decisions are now being made by multiple stakeholders driven by national health system demand for economic, societal and cost benefits. Patient centricity is fast becoming one of the essential considerations for the future success of new drugs and biopharmaceutical company growth.