We determined the carriage rate of Neisseria meningitidis before and after hajj pilgrimage among a group (1) of 674 randomly selected Iranian pilgrims, and the effect of 500 mg of ciprofloxacin given 24 hours before return on the reduction of meningococcal carriers among another group (2) of 123 randomly selected Iranian pilgrims. Throat specimens taken 1 hour before departure on the hajj and immediately on return were cultured. Carriage rates of N. meningitidis in group 1 were 5.2% before and 4.6% after pilgrimage (P = 0.65); 3 new serogroups (Z, Z and A) were identified on return. In group 2, the carriage rate decreased from 8.1% to zero before and after pilgrimage.