Kawasaki disease is an acute vasculitis syndrome that typically occurs in children aged 1 to 4 years. Because there is no specific diagnostic test for Kawasaki disease, the diagnosis is made clinically based on specific characteristic signs and symptoms. Cases in which patients fall outside of the typical age range are uncommon and often challenging to diagnose because they have atypical presentations. This is especially true in infants, who rarely meet all the clinical criteria required for diagnosis. Patients at the extremes of ages often have a delayed diagnosis, which can lead to worse cardiac outcomes. We describe the cases of a young infant and an older adolescent who present with Kawasaki disease. These cases illustrate the challenge of diagnosing Kawasaki disease in patients beyond the typical age range. Both patients were return visits to the emergency department after inpatient stays. When fever persists longer than 5 days, clinicians must have a high index of suspicion for Kawasaki disease in all pediatric age groups to prevent treatment delay and disease sequelae.