Abstract This paper focuses on project portfolio risk categorisation. Based on literature, a list including risks characteristic for a project portfolio was developed. After the assessment procedure (using the Delphi method), when the expert consensus had been achieved, thirty-six project portfolio risks were selected. The applied research procedure assumed project portfolio risk assessment, according to the approach suggested in the literature of the subject, including the likelihood of a given risk. During the research work, for the data clustering, exploratory factor analysis (EFA) has been applied. As a result of the analysis, a taxonomy of project portfolio risks was developed and a risk category with the greatest likelihood of occurrence was indicated.