Inherited complement deficiency is a rare disease. It predisposes to autoimmune diseases, glomerulonephritis, angioedema, and meningococcal meningitis. A prospective study was conducted over five years. The goal was to evaluate the prevalence of deficiency in Tunisian patients presenting with community acquired purulent meningitis and identify the type of deficiency. We enrolled 122 patients, 15 of whom presented with a complement deficiency (12.3%). This prevalence was higher than the one observed in the global Tunisian population and in reported international data. The mean age of deficient patients (13 men and two women) was 24.7 years.