 The Biobank Japan BBJ project was launched in 2003 to construct a large patient-based biobank and collect clinical information and DNA samples from patients diagnosed with common diseases. During the first five years, 200,000 participants were registered, and follow-up surveys were performed for participants with any of 32 diseases. The BBJ project has provided important clues for the implementation of personalized medicine. This article was authored by Akiko Nagai.