Severe congenital neutropenia (SCN) and Clostridium septicum myonecrosis is an uncommon and life-threatening association requiring urgent combined aggressive medical and surgical management. We report 2 cases of SCN (1 with known Kostmann's syndrome and 1 not known at presentation to have a congenital neutropenic disorder but subsequently received a diagnosis of cyclic neutropenia) who presented with spontaneous C septicum myonecrosis. The cases highlight the importance of response to recombinant human granulocyte colony-stimulating factor in obtaining a satisfactory outcome for these patients. Early, empirical use of recombinant human granulocyte colony-stimulating factor in patients who are suspected of having a congenital neutropenia and who present with life-threatening sepsis is recommended.