Background To evaluate the effectiveness and sustainability of self-managed sodium restriction in patients with chronic kidney disease. Study Design Open randomized controlled trial. Setting & Participants Patients with moderately decreased kidney function from 4 hospitals in the Netherlands. Intervention Regular care was compared with regular care plus an intervention comprising education, motivational interviewing, coaching, and self-monitoring of blood pressure (BP) and sodium. Outcomes Primary outcomes were sodium excretion and BP after the 3-month intervention and at 6-month follow-up. Secondary outcomes were protein excretion, kidney function, antihypertensive medication, self-efficacy, and health-related quality of life (HRQoL). Results At baseline, mean sodium excretion rate was 163.6 ± 64.9 (SD) mmol/24 h; mean estimated glomerular filtration rate was 49.7 ± 25.6 mL/min/1.73 m2; median protein excretion rate was 0.8 (IQR, 0.4-1.7) g/24 h; and mean 24-hour ambulatory systolic and diastolic BPs were 129 ± 15 and 76 ± 9 mm Hg, respectively. Compared to regular care only (n = 71), at 3 months, the intervention group (n = 67) showed reduced sodium excretion rate (mean change, −30.3 [95% CI, −54.7 to −5.9] mmol/24 h), daytime ambulatory diastolic BP (mean change, −3.4 [95% CI, −6.3 to −0.6] mm Hg), diastolic office BP (mean change, −5.2 [95% CI, −8.4 to −2.1] mm Hg), protein excretion (mean change, −0.4 [95% CI, −0.7 to −0.1] g/24h), and improved self-efficacy (mean change, 0.5 [95% CI, 0.1 to 0.9]). At 6 months, differences in sodium excretion rates and ambulatory BPs between the groups were not significant, but differences were detected in systolic and diastolic office BPs (mean changes of −7.3 [95% CI, −12.7 to −1.9] and −3.8 [95% CI, −6.9 to −0.6] mm Hg, respectively), protein excretion (mean changes, −0.3 [95% CI, −0.6 to −0.1] g/24h), and self-efficacy (mean change, 0.5 [95% CI, 0.0 to 0.9]). No differences in kidney function, medication, and HRQoL were observed. Limitations Nonblinding, relatively low response rate, and missing data. Conclusions Compared to regular care only, this self-management intervention modestly improved outcomes, although effects on sodium excretion and ambulatory BP diminish over time.