Introduction Previous research in children with Hirschsprung's disease (HD) and Down's syndrome (DS) has focused on colorectal outcomes. We set out to review urinary outcomes in this patient group. Methods The medical records of all patients aged five years and older with HD were reviewed, and patients and caregivers filled out the Vancouver Symptom Score at intake, which is designed and validated to diagnose dysfunctional elimination syndrome. Results A total of 104 patients with HD were included in this study. Of these, 16 (15%) patients had DS. There were no significant differences in the prevalence of enterocolitis or colorectal symptoms between patients with or without DS. Five of 88 (6%) patients without DS and 7 of 16 (44%) (p = 0.00001) with DS reported having urinary accidents. Patients with HD and DS scored higher on the Vancouver score (9 vs. 17.5; p = 0.007), indicating more severe urinary symptoms. Patients who also reported fecal accidents scored significantly higher on the Vancouver (12 vs. 9; n = 61; p = 0.016), indicating more problems. Conclusion Patients with DS appear to be a unique subset of HD patients who have a higher prevalence of urinary symptoms after surgery. In the postoperative care of patients with HD and DS, a strong focus should be placed on postoperative urinary care in addition to their bowel care. This could significantly ease care and contribute to the quality of life of the parents and the patient.