The literature does not commonly describe cardiac rhythm disturbances, including bradycardia, in patients who are receiving corticosteroids, and the exact mechanism of such disturbances remains unknown. Herein, we present a case of sinus bradycardia associated with stress-dose corticosteroid therapy. A nine-year-old boy with a history of panhypopituitarism was admitted with gastroenteritis and pneumonia and developed septic shock on the day of admission. Management using intravenous fluids, stress doses of hydrocortisone, and antibiotics resulted in full recovery. However, within 24 hours following treatment, sinus bradycardia was documented, with a heart rate of 45 beats per minute (BPM). The bradycardia resolved after the dose of hydrocortisone was decreased gradually. Corticosteroidinduced sinus bradycardia is an adverse effect that usually resolves after corticosteroid treatment is discontinued. During stress-dose corticosteroid therapy, hemodynamic monitoring should be considered. To our knowledge, this is the first report of sinus bradycardia following the use of hydrocortisone in children who have adrenal insufficiency.