The paper presents a study of the psycho-affective factor of anxiety experienced by Polish-English certified interpreters while performing certified consecutive interpreting. The first part of the article sketches the theoretical background of the study, by focusing on interpreter psychology, a subfield of interpreting studies offering the methodological scaffolding for the study of interpreting-related psychological phenomena, and on anxiety as one of the components of the interpreter’s psycho-affectivity. What follows is an overview of certified interpreting in the Polish context. The major part of the article provides an insight into the study of the certified interpreters’ experience of anxiety—its types, causes, linguistic and extra-linguistic manifestations. What emerges from the study is that anxiety is quite a potent psycho-affective factor which is likely to obstruct certified interpreting performance and lower the quality of its outcome—the oral output.