W iskott-Aldrich syndrome (WAS) is a primary immunode- ficiency disorder, characterized by a classic triad of microthrombocytopenia, eczema and infections. It is a monogenic X-linked recessive disorder. X-linked thrombocy- topenia (XLT) is now part of this syndrome with clinical forms initially described as less severe, but whose non-serious evolution is now questioned. WAS/XLT usually occurs during childhood, but a neonatal onset is possible. This pathology is associated with an increased risk of autoimmune manifesta- tions and onco-hematological complications which can occur regardless of the initial severity. The first manifestations are hemorrhagic (petechiae, bruising, purpura, epistaxis, oral or intracranial bleeding, bloody diarrhea). The second characte- ristic is acute or chronic eczema. Due to the immune deficiency, there are infectious manifestations (airways, digestive tract, skin) due to conventional or opportunistic bacteria. The severity of the disease, in addition to severe infectious complications, is linked to autoimmune manifestations in more than 40% of cases (hemolytic anemia and/or autoimmune neutropenia, vasculitis, inflammatory colitis, glomerulopathy, inflammatory joint pathologies). Patients with WAS also have an increased risk of developing tumors (especially lymphomas) at any age. Therapeutic progress in recent years are based on better management of complications, better results of bone marrow transplantation and development of gene therapy.