BACKGROUND: Knowing how kidney disease progresses is important for decision making in patients with chronic kidney disease (CKD) and for designing clinical services. STUDY DESIGN: Prospective cohort study. SETTING & PARTICIPANTS: We examined renal function trajectories in CRISIS (Chronic Renal Insufficiency Standards Implementation Study), in which 1,325 patients with CKD stages 3-5 and mean age of 65.1 years were followed up prospectively for a median of 26 months after referral to a regional nephrology center in the United Kingdom. By protocol, estimated glomerular filtration rate was determined every 12 months. PREDICTORS: CKD stage defined as estimated glomerular filtration rate ≥ 45 (stage 3a), 30-44 (3b), 15-29 (4), and < 15 (5) mL/min/1.73 m². OUTCOMES: Onset of renal replacement therapy (RRT), death, the composite end point of RRT or death, or decreasing CKD stage. RESULTS: During a median follow-up of 26 months, 13% reached the end point of RRT (5.1 events/100 patient-years), 20% died (9.6 deaths/100 patient-years), and 33% reached the combined end point of RRT or death (14.7 events/100 patient-years). For stage 3a, baseline prevalence and annual probabilities of decreasing CKD stage, RRT, and death were 18.0%, 0.41, 0.01, and 0.02, respectively. Corresponding values for stage 3b were 32.5%, 0.22, < 0.01, and 0.06; for stage 4, 36.5%, 0.17, 0.03, and 0.10; and for stage 5, 13.2%, zero (by definition), 0.31, and 0.08, respectively. Markov model projections suggested a steady decrease for proportions with stages 3a, 3b, and 4; a steady increase for death and RRT; and a biphasic pattern for (non-RRT) stage 5, with a plateau in the first 2 years followed by a steady decrease. LIMITATIONS: Single-center observational study. CONCLUSION: This study suggests that death and RRT are the dominant outcomes in patients referred for management of CKD and that most patients spend comparatively little time in late stages without RRT.