Although construction is a project-based industry, management focus has recently shifted from projects to project portfolios to meet strategic objectives of companies that require holistic analysis of the projects undertaken. Dependencies between projects within a portfolio need to be taken into consideration since they may significantly affect the portfolio success with their combined effects. There are limited studies in the area of construction project portfolio management that investigate how the dependencies between projects can be handled. In this paper, a method is presented to calculate and visualize project dependencies to support decision making process within a portfolio management tool for construction projects. Within this context, a dependency map is proposed not only to identify different dependencies and their effects within the portfolio, but also to take into consideration the combined effect of dependencies. An illustrative case study is depicted in the paper to demonstrate how the proposed method works and how its results can be used to support decision-making during portfolio selection.