The purpose of this study is to assess patients' aesthetic perceptions of interdental "black triangles", both in terms of the number of triangles visible and their severity; and to ascertain how patients rank the presence of "black triangles" against other aesthetic problems. It is based on a questionnaire of 80 randomly selected individuals who were asked to rate the aesthetics of digitally-manipulated images. Patients'perceptions of interdental "black triangles" were compared with their perceptions of other 'non-aesthetic' features. Interdental "black triangles" were rated as the third most disliked aesthetic problem below caries and crown margins. This study demonstrates the importance of interdental "black triangles" to patients, and therefore, as they can occur during prosthetic treatment, must be discussed with patients prior to commencing therapy.