The positive impact of air transport liberalisation as suggested by economic theories and empirical studies has inspired many developing countries like Nigeria to liberalise some of its Air Service Agreements (ASAs). This paper seeks to examine the extent to which international air service liberalisation has impacted upon Nigeria ten years after it was introduced. The research developed a cross-sectional model with passenger traffic as the dependent variable, while macroeconomic factors (trade and GDP), historical links, distance and ASAs (a proxy for liberalisation) served as independent or predictor variables. The analysis revealed a set of ASA stages in the country's policy-making process (restricted Bilateral Air Service Agreement, Open Skies Agreement and Yamoussoukro Declaration). Further analysis showed that the predictor variables were all significant in explaining passenger demand. The model demonstrated that the liberalisation of market access to the Open Skies Agreement level could stimulate traffic growth by at least 65 percent. The findings can assist in guiding policy and industry stakeholders in future decisions relating to liberalisation and ASAs. [Authors' abstract]