The aim of this study was to characterise different etiologies for the development of macular holes in diabetic retinopathy. We examined 8 eyes of 8 patients with known diabetic retinopathy who had developed a macular hole. These were classified as follows: related to macular edema (4 eyes), non-related to macular edema (2 eyes), intraoperative (1 eye) or postoperative (1 eye) after pars plana vitrectomy for proliferative diabetic retinopathy. In three patients the macular holes were treated with pars plana vitrectomy and fluid air exchange. In diabetic eyes with macular edema, macular holes may develop because of intraretinal exudation combined with increased vitreomacular attachments and tractions. The mechanism of macular hole formation in diabetic eyes without macular edema probably results from the same increased tangential vitreous traction which is seen in idiopathic age-related macular holes. Iatrogenically induced macular holes during pars plana vitrectomy for proliferative diabetic retinopathy may be also due to intraoperative vitreoretinal tugging. Finally, macular holes developing after vitrectomy may have an etiology not related to vitreous tractions or attachments.