Although modern clinical trials are traditionally conducted in Western countries, currently there is a shift to involve developing countries, particularly China and India. For these trials, the large population size of India and China means that substantial numbers of individuals affected by rare diseases may be found, increasing the likelihood of successfully completing enrollment in a clinical trial. Furthermore, the increasing involvement of Asian countries in global clinical trials is likely to lead to greater appreciation of the value of evidence-based treatment decisions in the region. These sites are more cost-effective, although this advantage is being eroded over time. Asian participants in clinical trials are also typically more likely to complete study follow-up and procedures, and to adhere to their randomized treatment allocation than individuals from Western countries. Challenges include relevance of the proposed trial to the region, capacity limitations because of undeveloped training, and ensuring research implementation quality and different intellectual property practices. There are specific challenges to conducting clinical trials in India, such as the status of ethics committees, health insurance and coverage for participants, and variability in languages and record-keeping. Challenges in both countries are substantial but are able to be managed with appropriate planning.