To determine the incidence of diabetic retinopathy (DR) progression after phacoemulsification in patients with type II diabetes. Service of Ophthalmology, University of Sant Joan, Barcelona, Spain. This prospective study evaluated 132 patients with diabetes mellitus who had monocular phacoemulsification. A control group comprised the patients' contralateral eyes. Data analysis included preoperative retinal findings and DR status; hemoglobin A1c (HbA1c), low-density lipoprotein cholesterol, and triglycerides levels; insulin treatment; and arterial hypertension. Postoperative visual acuity increased by 2 or more lines in 105 patients (79.55%); the mean postoperative acuity was 0.63 +/- 0.28 (SD). Diabetic retinopathy in the operated eye progressed in 31 patients (23.48%) and in the fellow eye in 28 patients (21.21%). The progression was associated with high levels of HbA1c and diabetes mellitus duration in both groups. Diabetic macular edema occurred in the operated eye in 8 patients (6.06%) and in the fellow eye in 6 patients (4.54%). Pseudophakic macular edema developed in 2 eyes (1.52%). The progression of diabetic macular edema was not associated with the risk factors studied. Uneventful phacoemulsification cataract surgery may not cause DR progression.