In non-diabetic patients with nephrotic syndrome (NS) at early stages of chronic kidney disease, it remains unclear whether the degree of proteinuria affects the nocturnal blood pressure (BP) dip. We evaluated the relationship among circadian BP rhythm, proteinuria and hypoalbuminemia in these patients. We also evaluated the autonomic nervous activity. Twenty-four-hour BP was measured in NS patients (8 men and 13 women; mean age, 58.5+/-14.8 years) and age- and sex-matched normal subjects (11 men and 13 women; mean age, 54.3+/-18.2 years) as controls. Serum albumin and urinary protein concentrations were measured. Power spectral analysis of the heart rate was performed, and the high frequency (HF) and low frequency (LF) components were calculated as indices of sympathovagal balance. There were no differences in waking BP between the NS and the control groups (131+/-13/78+/-9 vs. 130+/-17/76+/-7 mm Hg; P>0.05). However, sleeping BP was significantly higher in the NS group than in the control group (127+/-18/75+/-9 vs. 115+/-14/66+/-7 mm Hg; P<0.05). Sleeping/waking BP ratios were higher in the NS group than in the control group (P<0.01). In the NS group, these ratios correlated significantly with serum albumin level (r=-0.54, P=0.011 for systolic BP; r=-0.48, P=0.030 for diastolic BP) and urinary protein excretion (r=0.47, P=0.027 for systolic BP; r=0.60, P=0.003 for diastolic BP). Both HF components and LF/HF ratios were not significantly different between the two groups. In non-diabetic NS patients, loss of nocturnal BP reduction correlates with proteinuria and hypoalbuminemia but not with circadian autonomic nervous rhythm.