Congenital Neutropenia (CN), the maturation of the neutrophils stops at promielocyte stage. The aim of the study: emphasizing a timely diagnosis. Case 1: V.A a 5-year-old girl presents from the age of 5 months: pneumonia, acute persistent diarrhea, anemia, leukocytosis and neutropenia. She was diagnosed with Acute Lymphoblastic Leukemia developed on the field of CN. Treatment was administered. Since the completion of the treatment she has remained in remission. Case 2: T.V.D. a 14-year-old boy presents from the age of 4 months recurrent infections: gingivitis, stomatitis, mucositis, pneumonias, otitis media. Hypoacusis results despite ethiologic treatment. Case 3: 15 year-old girl B.K. is admitted to hospital for the investigation of the recurrent infections from the age of 3 months. The investigations show CN, iron deficiency and anemia. NC is a rare disease that manifests itself by various infections since childhood. The administration of Neupogen is giving encouraging results. Malignant transformation is frequent.