Data suggest increased rates of chronic kidney disease (CKD) in those with undiagnosed hypertension (HTN). Our study aimed to determine the prevalence of CKD in undiagnosed hypertensives in a previously unreported subgroup of individuals of South Asian ethnicity. We analysed data from subjects in the ADDITION-Leicester study, a UK based multiethnic, community diabetes screening study. Standard definitions included: HTN-mean recorded BP of ⩾140/90 mm Hg, CKD stage 3 and above-estimated glomerular filtration rate (eGFR) <60 ml min(-1) per 1.73 m2 and microalbuminuria as albumin creatinine ratio ⩾3 mg mmol(-1). Logistic regression was performed with age, gender and body mass index (kg m(-2)) as co-variates. 6082 individuals (52.5% female, mean age, 57.2 years; White European, 77.8% and South Asian, 22.0%), 31.1% had undiagnosed HTN. Overall, individuals with undiagnosed HTN compared with normotensives had an odds ratio for microalbuminuria of 2.24 (95% confidence interval (CI): 1.72-2.94). For South Asians, the odds ratio was 3.81. (95% CI: 2.24-6.47) for microalbuminuria with a trend towards an eGFR<60 ml min(-1) per 1.73 m2. Future studies should consider intensified screening for HTN to refine the population suitable for CKD screening, particularly in the South Asian ethnic group.