OBJECTIVE: To define glomerular filtration rate (GFR) decline, hypertension (HTN), and proteinuria in subjects with autosomal recessive polycystic kidney disease (ARPKD) and compare with 2 congenital kidney disease control groups in the Chronic Kidney Disease in Children cohort. STUDY DESIGN: GFR decline (iohexol clearance), rates of HTN (ambulatory/casual blood pressures), antihypertensive medication usage, left ventricular hypertrophy, and proteinuria were analyzed in subjects with ARPKD (n = 22) and 2 control groups: aplastic/hypoplastic/dysplastic disorders (n = 44) and obstructive uropathies (n = 44). Differences between study groups were examined with the Wilcoxon rank sum test. RESULTS: Annualized GFR change in subjects with ARPKD was -1.4 mL/min/1.73 m(2) (-6%), with greater decline in subjects age >/=10 years (-11.5%). However, overall rates of GFR decline did not differ significantly in subjects with ARPKD vs controls. There were no significant differences in rates of HTN or left ventricular hypertrophy, but subjects with ARPKD had a greater percent on >/=3 blood pressure medications (32% vs 0%, P < .0001), more angiotensin-converting enzyme inhibitor use (82% vs 27% vs 36%, P < .0005), and less proteinuria (urine protein: creatinine = 0.1 vs 0.6, P < .005). CONCLUSIONS: This study reports rates of GFR decline, HTN, and proteinuria in a small but well-phenotyped ARPKD cohort. The relatively slow rate of GFR decline in subjects with ARPKD and absence of significant proteinuria suggest that these standard clinical measures may have limited utility in assessing therapeutic interventions and highlight the need for other ARPKD kidney disease progression biomarkers.