RATIONALE: Late complement deficiency increases susceptibility to meningococcal disease and recurrent infections. In Korea, 5 case reports have described meningococcal disease with complement deficiency. However, C6 deficiency has not been described previously. PATIENT CONCERNS: A 21-year-old police trainee presented with recurrent meningococcal meningitis. He was housed in communal living quarters until 20 days before the initial symptom onset. DIAGNOSIS: He was diagnosed with meningococcal meningitis with C6 deficiency. INTERVENTIONS: He was treated with intravenous ceftriaxone. An additional dose of quadrivalent meningococcal conjugate vaccine was administered after discharge. OUTCOMES: He was discharged without complications. LESSONS: Screening for complement deficiency is necessary in patients with a history of recurrent meningococcal infections to provide appropriate care and prevent recurrent infections.