Objective To investigate the risk factors of the intraocular pressure (IOP) elevation after pars plana vitrectomy (PPV). Methods Eighty-eight patients (88 eyes) of postoperative ocular hypertension in a series of 339 patients who had undergone PPV with normal ocular pressure before operation were retrospectively studied. The ocular pressures in both preoperative and postoperative periods were detected by NCT examination, and the ocular hypertension was decided on the level of ≥25 mm Hg. The relationships of occurence of the time of onset and duration of persistence of postoperative ocular hypertension with the different kinds of primary diseases, the techniques of operation, and the condition whether or not the affected eyes had formerly accepted surgical intervention, were analyzed. Results The IOP elevation occures mostly within 1 to 2 weeks postoperatively (77 eyes, 87.5%). In 65 cases (65 eyes) IOP returned to normal in 1 week, and in another 14 cases (14 eyes) in 1 month after treatments. Six patients’ (6 eyes ) IOP was under 25 to 30 mm Hg with the medicine. With sustained elevation of IOP over 4 to 6 months, 3 cases (3 eyes ) lost or almost lost their vision finally. The probability of postoperative IOP elevation in the patients suffered from the retinal detachment with proliferative vitreoretinopathy (PVR) ≥grade C-2 was the highest in all the patients in our study (38.2%, P＜0.05). The patients who had intraocular surgery before were more likely to have IOP elevation than the ones without intraocular surgery (P＜0.05). Placement of a scleral buckle, use of expansile gases or silicone oil injection and scatter endophotocoagulation intraoperatively were related to the postvitrectomy IOP elevation (γ=0.829, P＜0.001). Conclusions The previous intraocular surgeries, certain primary eye diseases and combined ocular procedures are the risk factors of IOP elevation after PPV. (Chin J Ocul Fundus Dis, 2002, 18: 106-108)