OBJECTIVES: To explore the clinical pharmacy services and workforce requirements at Ministry of Health (MOH) Hospitals during mass gathering Hajj ten years (2006-2015) at Makah and Al-Medina Regions in Saudi Arabia METHODS: It is a retrospective analysis of ten years (2006-2015) of MOH hospital pharmacies during mass gathering Hajj period (15-30 days). The clinical pharmacist should provide pharmaceutical to all patients either Pilgrim or not Pilgrim at Makah region. The workforce requirements calculated based on MOH workforce standards of hospitals. The clinical activities drive from MOH critical care services, and emergency services, and mortality rate data. American College of Clinical Pharmacy (ACCP) model of clinical activities used. RESULTS: In Makah Region; The total number of prescriptions (99,886-257,545) with average (180,120), it represented (5.11-12.07%) with average (7.86%) of all pilgrims. In Al-Medina Region; the total number of prescriptions (35,149-207,444) with average was (142,080). It represented (1.48-8.35%) with an average (5.79 %) of all pilgrims. The average number of clinical pharmacists needed was (15.39 FTE) per each hospital at holy places, (21.69 FTE) per each hospital Makah city, and (18.54 FTE) per each hospital at Makah. The average number of clinical pharmacists needed was (15.6 FTE) per hospital in Al-Medina. The central pharmacy activities need (4 FTE) of clinical pharmacist per each hospital in Makah region, while in Al-Medina region was (3 FTE). The patient-centered clinical pharmacy services need (10 FTE) of clinical pharmacist per each hospital in Makah and Al-Medina regions. The administrative, clinical pharmacy activities need (4 FTE) of clinical pharmacist per each hospital, while (3 FTE) at Al-Medina region. CONCLUSIONS:  The clinical pharmacy services are essential during mass gathering Hajj period. The clinical pharmacy services prevent drug-related mortality and morbidity during Hajj period. Also, improve patient clinical outcome, patient quality of life, and avoid the unnecessary cost