Background Chronic kidney disease is a serious and complex medical condition which affects a significant number of people in the UK. Guidance from NICE currently recommends referral of CKD patients at stages G4-5 but the guidelines themselves are not based on strong evidence. Objectives To compare progression rates for CKD G3 patients in primary and secondary care groups to determine whether or not earlier referral should be supported. Methods We categorised 1,345 patients with stage G3 CKD into primary and secondary care and further subdivided secondary care into non-renal and renal groups. Baseline differences between primary and secondary care groups were explored via Student t-tests and chisquared analyses. Baseline exploratory analysis of potential relationships between eGFR and other variables was done via simple linear and multiple regression modelling. Longitudinal trends were described using linear mixed effects modelling and chi-squared tests were used to compare differences in all-cause mortality and end-stage renal disease rates. Results The overall trend was an improvement in renal function by 1.26 ml/min/1.73 m2 per year over an average follow up period of 2.84 years. Trends for primary, non-renal secondary and renal secondary care were 1.84, 0.87 and -0.17 ml/min/1.73 m2 per year respectively. The relative risk of all-cause mortality was 2.49 times greater for secondary care patients compared to primary care (p<0.001). Conclusions The management of CKD G3 patients in primary care is able to defer renal decline for at least 2.84 years. Most patients who are at higher risk of progression are already identified and referred to secondary care. Overall this supports current NICE guidelines on referral.