OBJECTIVE: Meningococcal meningitis epidemics, which occurred in the Kingdom of Saudi Arabia (KSA) coincided with Hajj and Umra seasons; the 2 major pilgrims to Muslims. In many countries, the disease showed major changes of its epidemiological determinants, in particular to age and prevailing serogroup. This study was conducted to determine the epidemiological trend of meningococcal meningitis disease in KSA. METHODS: All confirmed meningococcal meningitis cases reported in KSA during the period from January 1999 to December 2002 were studied retrospectively. Confirmation of cases was based on isolation of the causative organism from cerebrospinal fluid (CSF) or blood culture or detection of antigen in the CSF. Personal, clinical and laboratory results were analyzed using Epi info version 6 software. Categorical data were tested using chi2 test. RESULTS: A total of 729 cases were reported, 304 cases (42\%) were among people coming from abroad for Hajj or Umra and 425 (58\%) were among local population. Nearly half of the later (48\%) were reported at the 2 holy areas of Makkah and Madinah, KSA. Thirty-nine percent of cases were children aged \textless2 years and 58\% were \textless5 years of age. Proportion of cases affected with serogroup W135 increased over time (up to 95\%) and significantly affected children aged \textless5 years (p\textless0.001). CONCLUSION: Continuous monitoring of epidemiological determinants is essential to guide vaccination policy.