A prospective gonioscopic evaluation was carried out upon a cohort of Greek patients who had undergone trabeculectomy for open-angle glaucoma. Sixty-five patients were found to show clinical evidence of exfoliation glaucoma (EXG), whilst nine patients were deemed to have primary open angle glaucoma (POAG). The gonioscopic features of these eyes and of 43 non-operated eyes from the same patients with either exfoliation syndrome (EXS) or EXG are presented. The median degree of angle pigmentation was significantly higher in the operated eyes with EXG when compared with the POAG cases. In the operated eyes, deposition of exfoliation was found on the ciliary processes in 82% of cases and on the zonules in 52%.