AIM:To evaluate the clinical effects of Terson syndrome. METHODS:Thirteen cases（19 eyes）of Terson syndrome had preoperative visual acuity (VA) from light perception to 0.02, and duration of 1-15 (average 7.7) months. Vitrectomy was performed.In accordance with the vitreo-retinal circumstances, silicone oil tamponade was performed on 2 eyes, gas filling on 1 eye，others were filled with vitrectomy perfusate. RESULTS:Majority of vitreous hemorrhage was found concentrated in the posterior pole; preretinal hemorrhage occurred in 12 eyes( symmetrical in two eyes), hemorrhage in the macular area in 4 eyes, multi-focal hemorrhage in 3 eyes.After the first operation, VA in 19 eyes significantly increased, VA in 12 eyes without macular preretinal hemorrhage increased to 0.4-1.0 (average 0.6); VA in 4 eyes with macular preretinal hemorrhage increased to 0.02-0.4 (average 0.3).The former significantly increased in VA than the latter (P<0.05). Postoperative follow-up on 15 eyes lasted for 3 to 26 (mean 17.6) months. Postoperative retinal detachment occurred in 2 eyes, which got satisfactory result from retinal reattachment surgery. CONCLUSION:Timely vitreoretinal surgery is safe and effective for Terson syndrome patients. Visions in patients without macular preretinal hemorrhage are restored better than those with macular preretinal hemorrhage.