Incontinentia pigmenti (IP) is an uncommon X-linked dominant multisystem disorder, lethal in the majority of affected males in utero and variably expressed in females. The cutaneous manifestations are diagnostic and classically occur in four stages: vesicular, verrucous, hyperpigmented, and atrophic. The skin lesions are typically spread along the lines of Blaschko, and they are usually present at birth. It may be variably accompanied by dental, ocular, neurologic, bones and joints, and development anomalies. The genes IP has been mapped to Xq28. Mutations in the NEMO/IKKγ gene, located at Xq28, have been found to cause expression of the disease. Behçets disease is a multisystem disorder consisting of recurrent oral aphtae, genital ulcers, pustular skin eruption, and uveitis. Occasionally there are other articular, neurological, intestinal, or vascular abnormalities. This disease is rare in children. Here, we report a case of a 16-year-old female with the rare combination of incontinentia pigmenti and an aphthosis bipolar, and we discuss the probably relationship between these two diseases.