The China Kadoorie Biobank (CKB) involves over 0.5 million individuals aged 30-79 recruited during 2004-8 from 10 diverse regions of China, with extensive data collection at baseline and long-term storage of plasma (in Oxford and Beijing) and DNA-containing buffy coat (in Beijing). This resource will support a diverse range of research to assess the relevance for common chronic diseases of known and novel lifestyle, environmental, biochemical and genetic risk factors and their interactions. Chronic disease such as cancer, stroke, and coronary heart disease are now substantial causes of death and disability in low- and middle-income countries such as China. Several important causes of major chronic diseases are well established, but this knowledge is mainly based on studies in the West and may not explain much of the large heterogeneity in disease rates between Asian and Western populations or between different regions within China. Moreover, genetic risk factors and gene-environment interactions – that are likely to play important roles in disease aetiology – may also differ between Asian and Western populations. Although case-control studies may suffice for the study of purely genetic factors, large blood-based prospective studies are essential for the unbiased assessment of the relevance of both genetic and environmental factors, and their interactions. Following the baseline assessment of all 0.5 million participants, a resurvey of 20,000 participants was completed in 2008 and a second resurvey of around 25,000 commenced in 2013 to allow for appropriate correction for time-dependent regression dilution bias, with additional phenotyping enhancements (e.g. ECG, carotid IMT). Reliable linkage to electronic hospital treatment records has now been established in each study area. Participants are being followed up for cause-specific mortality and episodes of hospitalisation, with large enough numbers of disease events having already accumulated for prospective analyses of associations with a range of lifestyle and environmental factors. Independent validation and adjudication of outcomes has commenced for several major diseases (e.g. cancer, stroke, and coronary heart disease) that will improve disease phenotyping. Various high-throughput multi-omics technologies (e.g. GWAS, NMR) and standard assays will be used in “nested” case-control studies to assess the relevance of a wide range of known and novel blood-related factors to the onset rates of particular types of cancer, particular types of stroke, IHD, diabetes, lung disease and several other diseases.