AIM:To investigate the changes of intraocular pressure (IOP) and associated factors of IOP elevation after posterior sub-Tenon’s capsule (PST) injection with triamcinolone acetonide (TA) for macular edema. METHODS:The study included 46 cases(46 eyes) who received PST injections of 20mg TA to treat macular edema with diabetic retinopathy (n=16),age-related macular degeneration (n=13), retinal vein occlusion (n=11),and posterior uveitis (n=6). IOP measurements were performed on the day of injection, and 2 weeks，1 month，2, 3, 4, 5 and 6 months later. RESULTS:The mean IOP of all eyes showed a gradual increase after the injection, peaked at 3 months (19.22±6.86mmHg), and then decreased gradually until reaching a minimum at 6 months. Of the 46 eyes, 17(37%) showed an IOP above 21 mmHg at 3 months post-injection. Compared with the pre-injection, the mean IOP increased significantly at 2 weeks，1 month，2，3，4，5 months（t value were 3.747, 5.836, 5.982, 5.866, 4.202, 3.246 respectively, all P<0.05）, however, there was no significant difference between the pre-injection and the 6 months post-injection (t=1.446,P>0.05) . And IOP elevation significantly correlated with younger age（χ²=5599，P<005）and higher baseline IOP（χ²=10.323，P<005）, but not with gender（χ2=0.022，P>0.05）or disease（χ^{2=0.050，P>0.05）. CONCLUSION:E1evation of IOP after PST injection with TA is not rare and the peak level usually occurs at 3 months post-injection, and then the IOP decreases gradually to approach the baseline level until 6 months post-injection. Younger age and higher baseline IOP are identified as risk factors. Our findings indicate that careful assessment of IOP during a follow-up at least 6 months is necessary，especially in those who are younger or with higher baseline IOP.}