Sharing knowledge through inter-organizational relationships is one means of enhancing strategic competitiveness. It is generally agreed that the development of close relationships facilitates such sharing among partners. This paper presents a research model comprises five research hypotheses with four constructs, including moral orientation, opportunistic behavior, loss of competences risk and knowledge sharing. This study develops a conceptual model that relational risk as a mediating construct to examine the inter-relationship effects that affect knowledge sharing and these relationships. We analyze data collected from 281 major manufacturing firms in Taiwan, using structural equation modeling. The results of the empirical study suggest that the role played by moral orientation is critical in ensuring the knowledge sharing as it mitigates the opportunistic behavior and loss of competences risk in the process. The findings of the study provide useful insights into how supply chain members should reinforce their collaborative behaviors and activities so as to improve their moral orientation and in turn enhance knowledge sharing for the supply chain as a whole.