Hong Kong International Airport (HKIA) is one of the main gateways to Mainland China and the major aviation hub in Asia. An accurate airport traffic demand forecast allows for short and long-term planning and decision making regarding airport facilities and flight networks. This paper employs the Box–Jenkins Seasonal ARIMA (SARIMA) model and the ARIMAX model to forecast airport passenger traffic for Hong Kong, and projecting its future growth trend to 2015. Both models predict a steady growth in future airport passenger traffic at Hong Kong. In addition, scenario analysis suggests that Hong Kong airport's future passenger traffic will continue to grow in different magnitudes.