The objective of the study was to investigate the utility of 24 h ambulatory blood pressure measurement (ABPM) in patients with chronic renal disease (CRD). A retrospective audit was performed in an academic nephrology department. ABPMs obtained from 95 consecutive outpatients with nondiabetic renal disease were analysed for their power to stratify disease severity and to predict progression of renal insufficiency during 3 years follow-up. The average of 10 consecutive office blood pressure (BP) readings performed at baseline was used as a reference. Correlations and tabulated statistics were calculated. Baseline mean diurnal BP was 138/87mmHg by ABPM and 146/92mmHg by average office BP (56.8 vs 25.3% normotensives, P<0.01). Mean serum creatinine was 1547109 mu mol/l. Patients without a circadian BP pattern (61%) had significantly higher serum creatinine, urinary albumin excretion and subsequent progression rates of renal failure (P<0.05). Systolic and pulse pressure ABP values correlated significantly with serum creatinine levels at baseline and 3 years thereafter, independent of daytime (r=0.23-0.60; P<0.05). Abnormal nocturnal systolic and mean ABP, and pulse pressure but not average day office BP were significantly associated with abnormal serum creatinine and the presence of coronary heart disease at baseline (relative risk 1.6-1.7, P<0.05). In conclusion, physicians considered ABPM preferentially in patients with borderline-controlled BP. ABPM provided significant additional information relevant to the clinical decision making process compared with average office BP alone thereby justifying its use in specific situations.