AIMS: The aim of this study was to report the development or progression of tractional retinal detachment (TRD) after the injection of intravitreal bevacizumab (Avastin) used as an adjuvant to vitrectomy for the management of severe proliferative diabetic retinopathy (PDR). METHODS: The clinical charts of patients who experienced the development or progression of TRD after an intravitreal injection of 1.25 mg bevacizumab before vitrectomy for the management of PDR were reviewed. RESULTS: Eleven eyes (patients) out of 211 intravitreal injections (5.2%) that developed or had progression of TRD were identified. All eyes had PDR refractory to panretinal photocoagulation (PRP). Nine patients had type 1 diabetes mellitus (DM), and two patients had type 2 DM. Patients had a mean age of 39.5 years (range 22-62 years). In the current study, all patients used insulin administration and had poor glycaemic control (mean HbA(1c) 10.6%). Time from injection to TRD was a mean of 13 days (range 3-31 days). Mean best correct visual acuity (BCVA) at TRD development or progression was logarithm of the minimal angle of resolution (LogMAR) 2.2 (range 1.0-2.6) (mean Snellen equivalent hand motions; range 20/200 to light perception), a statistically significant worsening compared with baseline BCVA (p<0.0001). Eight eyes underwent vitrectomy and three patients refused or were unable to undergo surgery. The final mean BCVA after surgery was LogMAR 0.9 (range 0.2-2.0) (mean Snellen equivalent 20/160; range 20/32 to counting fingers), a statistically significant improvement compared with TRD BCVA (p = 0.002). CONCLUSIONS: TRD may occur or progress shortly following administration of intravitreal bevacizumab in patients with severe PDR.