Abstract Background Chronic kidney disease (CKD) is associated with life style diseases such as hypertension and type 2 diabetes. However the role of diet is not yet clearly defined for development of CKD. Recent studies have shown that n-3 polyunsaturated fatty acids (PUFAs) may exert favourable effects on several processes that may inhibit the development and progression of CKD. A gold standard biomarker for long-term intake and metabolism of n-3 PUFAs, is their content in adipose tissue; because these fatty acids are essential and not endogenously produced. Aims The primary aim of this study is to investigate the association of adipose tissue content of marine and plant-based n-3 PUFAs to the risk of incident CKD. This study will also examine associations between the content of n-3 PUFAs in adipose tissue and the risk of main subtypes of CKD: Proteinuria with unknown cause, Hypertensive nephropathy, Glomerular diseases, Diabetic nephropathy and Chronic renal failure of unknown cause. Method In this case-cohort study based on data from the prospective Danish Diet, Cancer and Health cohort (DCH), information concerning diet and other lifestyle factors was obtained from 57,053 Danish men and women aged 50 to 65 years, using questionnaires and interviews. Anthropometric measurements were undertaken, and adipose tissue biopsies were taken from the buttocks of all participants at baseline. The follow-up period was from December 1993 to September 2017. The outcome CKD is defined as having a diagnosis of one of the CKDs causes in the Danish National Patient Registry (DNPR). Cases of CKD will be identified and included together with a randomly drawn subcohort, representative for all participants of the cohort. Adipose tissue samples will be analyzed by gas chromatography in all incident CKD cases and in 5,000 randomly drawn participants from the whole cohort. The outcome will be adjusted for age, sex, body mass index, physical activity, energy intake, alcohol consumption, fermented dairy products, education, smoking status, hormone replacement therapy and comorbidity. The study is approved by the Danish National Committee on Health Research Ethics (N-20180074) and the Danish Data Protection Agency (2018-139). Results No results are available yet. Conclusion Our hypothesis is that the content of total n-3 PUFAs, as well as both marine and plant-based n-3 PUFAs, in adipose tissue is inversely associated with the risk of CKD and its subtypes.