Objectives: This study aimed to describe inpatient clinical conditions at an advanced care facility in Saudi Arabia during the annual Hajj pilgrimage and to determine factors correlating with length of stay (LOS). Methods: This retrospective study was conducted at the King Abdullah Medical City (KAMC), Makkah, Saudi Arabia, and included all inpatients admitted during the annual Hajj pilgrimage between August and October 2015. Demographic, administrative and clinical data were collected from patient charts and analysed. Results: A total of 296 inpatients were included in the study, of which the majority were male (73.6%) and ≥55 years old (77%). Walk-in admissions occurred less frequently than referrals (38.9% versus 61.1%). Most patients (41.6%) were admitted during the peak Hajj period (the 8th-13th days of Dhu al-Hijjah). Acute coronary syndrome was the most prevalent provisional diagnosis (65.2%). In terms of outcomes, 89.2% of the inpatients were discharged in a stable condition, with 37.5% discharged within ≤24 hours of admission. However, 39.9% required admission to the Intensive Care Unit (ICU). Overall, LOS was significantly associated with various factors, including the mode of admission, admission period, admitting department, number of comorbidities and ICU admission (P <0.050 each). Conclusion: Most of admissions were referrals, and the main Hajj period witnessed the majority of admissions. The vast majority of inpatients eventually discharged in a stable condition. Determinants of the length of hospital stay were the mode of admission, admission period, admitting department, number of comorbidities and ICU admission.