BACKGROUND: In the UK, explicit quality standards for chronic disease management, including for diabetes and chronic kidney disease (CKD), are set out National Service Frameworks and pay-for-performance indicators. These conditions are common with a prevalence of 4% and 5.4%, respectively. CKD is largely asymptomatic, detected following renal function testing and important because associated with increased mortality and morbidity, especially in people with diabetes and proteinuria. OBJECTIVES: To investigate who has their renal function tested and any association with age, sex, ethnicity and diabetes. METHOD: A cross-sectional survey in a primary care research network in south-west London (n = 220 721). The following data were extracted from routine data: age, gender, ethnicity, latest serum creatinine, diagnosis of diabetes and recording of proteinuria. We used logistic regression to explore any association in testing for CKD. RESULTS: People (82.1%) with diabetes had renal function and proteinuria tested; the proportion was much smaller (<0.5%) in those without. Women were more likely to have a creatinine test than men (28% versus 24%, P < 0.05), but this association was modified by age, ethnicity and presence of diabetes. People >75 years and with diabetes were most likely to have been tested. Black [adjusted odds ratio (AOR) 2.1, 95% confidence interval (CI) 2.0-2.2] and south Asian (AOR 1.65, 95% CI 1.56-1.75) patients were more likely to be tested than whites. Those where ethnicity was not stated were the only group not tested more than whites. CONCLUSIONS: Quality improvement initiatives and equity audits, which include CKD should take account of disparities in renal function testing.