The complement system is composed of more than 25 different proteins and is usually divided into classical and alternative pathways. Complement component 7(C7) is one of the five terminal complement proteins that, upon activation of either the classical or the alternative pathway, interacts sequentially to form a large protein-protein complex, called membrane attack complex(MAC). Assembly of the MAC on target cells results in the formation of transmembrane pores that can lead to the killing of the cells. C7 deficiency is an autosomal recessive disorder that is mostly reported in Caucasians. The gene for C7 has been assigned to chromosome 5p13. To date, 15 different molecular defects leading to total or subtotal C7 deficient defects have been reported. C7 deficiency is associated frequently with recurrently bacterial infections, especially meningitis caused by Neisseria meningitidis. We report a case of a hereditary C7 deficiency associated with meningococcal meningitis.