International construction projects generally involve participants from different cultural backgrounds. In this type of projects, national culture can significantly influence knowledge sharing between individuals. This research contributes to the literature by providing a deeper understanding of cultural issues that influence knowledge sharing in international construction projects. The research was carried out in three international construction joint ventures located in Qatar, Libya, and Bulgaria. A mixed method design was used to better understand the research problem and strengthen the findings. The findings are interpreted through the cultural dimensions of Hofstede and Hall. Based on the analysis, language and communication difficulties, trust, motivation, and personal relationships were found as the critical barriers to successful knowledge sharing in multicultural project teams. Findings from this study can help managers to better understand the role of national culture in knowledge sharing in the context of improving project performance.