Primary complement deficiencies are rare and two related patients are reported here. The first patient is a 41- year- old man with eighteen episodes of pneumococcal meningitis and other purulent infections. The serum C3 level was checked at three separate times, showing that this was a primary C3 deficient case; other immunological tests were however normal. This patient now takes prophylactic antibiotics and the meningitis has not recurred, but he does have glomerulonephritis. The second case is a 40 - year-old woman with repeated episodes of orofacial and laryngeal edema and dyspnea. The serum C1INH levels were 4.3 to 7 mgldL which were very low compared with normal healthy subjects (C1INH was 40-50 mg/dL in ten normal controls) and C4 was lower than normal but other immunological tests were normal. Other causes of angioederna such as lymphoproliferative disorders were excluded. She had hereditary angioedema without a family background. The condition may be due to genetic mutation. The angioedema was controlled with Danazol and Stanasol. As our patients are related, this may suggest a genetic relationship between these two disorders.