In recognition of the failure of knowledge management initiatives and the reluctance of employees to fully utilise knowledge management systems, regardless of their usefulness and level of sophistication, research attention is turned toward investigating the barriers blocking the sharing of knowledge among individuals. Moreover, the value of sharing tacit knowledge, especially through face-to-face interactions, has always been acknowledged as an important prerequisite for achieving fruitful cooperation, within an organisation, and on-the-job problem solving, especially in the health services sector. With an aim to understand the drivers of sharing behaviour, this paper develops an extensive model, based on the social psychological theory of planned behaviour (TPB), to examine actual knowledge sharing behaviour of physicians and nurses at the ward level. The objective of this model is to integrate the influence of various factors, including extensions to the TPB (past behaviour, perceived moral obligation and self-efficacy), expected reciprocal relationships and commitment. The understanding of the sharing behaviour of individuals can assist the design and utilisation of such managerial interventions that can effectively support and enhance inter-organisational knowledge sharing.