An estimated 6000 patients who are undocumented immigrants have end-stage renal disease (ESRD) and routinely present to public safety-net hospitals for life-saving emergent dialysis treatments. Because these patients lack a dialysis unit, they often do not have access to medication management consistently coordinated by a nephrologist, and this can result in more frequent emergency department (ED) utilization and cost of care. We hypothesized that patients who were taking loop diuretics had fewer ED visits for emergency dialysis. Loop diuretics can potentially take advantage of residual renal function and mitigate excess fluid gain that can induce heart failure and high potassium, the two most common indications for emergency dialysis. In our univariable analysis, patients on furosemide had 3.1 fewer ED visits on average compared with patients who are not on furosemide. After adjusting for vintage and serum potassium measures, the average number of ED visits was about 1.1 visits less in furosemide-treated patients compared with patients not receiving furosemide (95% confidence interval, −4.4 to 2.1). These results suggest that loop diuretics may have an important role in undocumented patients with ESRD with residual renal function. Further study to develop practical approaches to the care of undocumented patients with ESRD is greatly needed.