Construction projects are prone to cost overruns and delays that can significantly impact their profitability and quality. Identifying the root causes of these issues is critical to finding practical solutions. This study focuses on the Egyptian construction sector and identifies the top six factors that lead to cost overruns and delays in mega construction projects. These factors are inadequate project planning, poor communication and coordination, changes in project scope, lack of skilled labour, insufficient budget allocation, and payment delays. The study recommends strategies to mitigate these factors, such as involving all stakeholders in the planning process, using project management tools, and setting realistic timelines to improve project planning and scheduling. Regular meetings and clear communication channels can achieve effective communication and coordination. The study also suggests managing changes in project scope through effective change management processes and ensuring sufficient budget allocation by conducting accurate cost estimates and setting aside contingency funds. These recommendations can provide practical insights for practitioners and policymakers in the construction industry to mitigate the impact of cost overruns and delays. Overall, the study emphasises the importance of identifying and addressing the key factors contributing to cost overruns and delays in mega construction projects.