The incidence of alloimmune neonatal neutropenia combined with neonatal alloimmune thrombocytopenia is very low. We report a case of a neonate who suffered severe neutropenia and thombocytopenia with widespread petechial spots. The presence of alloantibodies in mother's and patient's sera was analyzed by lymphocytotoxicity test, agglutination test, granulocyte indirect immunofluorescence test, platelet immunofluorescence test (PIFT) and solid phase enzyme-linked immunosorbent assay. Human neutrophil antigens (HNA) and human platelet antigen (HPA) genotypes were tested by polymerase chain reaction analyses. The mother's and patient's sera reacted with neutrophils and lymphocytes of the father. PIFT revealed the presence of IgG anti-platelet antibodies in the patient's serum but the test was negative in the maternal serum. Analyses of HNA-1 and HPA genotypes of the family revealed maternal-neonatal HNA-1a and HPA-3b mismatch. The study of the mother's and patient's sera showed the presence of anti HNA1a, HPA-3b and HLA antibodies specific for HLA-A3 and HLA-B38 antigens. These results suggest that the transplacental passage of maternal HNA-1a, HPA-3b and HLA alloantibodies caused neutropenia and thrombocytopenia in this patient.