We describe a patient who presented at 9 years of age with oral ulcers and cutaneous lesions, meeting diagnostic criteria for Behçet disease. At 11 years of age, she developed infectious complications and was proven to have chronic granulomatous disease, with characterization of the specific genetic mutation. We review available literature regarding overlap of these symptom complexes leading to delay in securing this important diagnosis. This is the second reported case of chronic granulomatous disease mimicking Behçet disease, and the first report to include identification of the specific genetic mutation of the nicotinamide adenine dinucleotide phosphate oxidase complex.