A survey of 2704 eyes with intraocular tumors in patients who were evaluated on the Oncology Service at Wills Eye Hospital showed that 126 of the tumor-containing eyes (5%) had tumor-induced elevated intraocular pressure (IOP) at the time of diagnosis of the tumor. Of the 2111 eyes with uveal melanomas, secondary IOP elevation was present in 55 (3%). Secondary IOP elevation was present in 7% of eyes with iris melanoma, 17% with ciliary body melanoma, and 2% with choroidal melanoma. The most common mechanism of elevated IOP was tumor invasion of the angle in the case of iris melanomas, pigment dispersion and tumor invasion of the angle in the case of ciliary body melanomas, and iris neovascularization in the case of choroidal melanomas. Of the 256 eyes with uveal metastases, secondary IOP elevation was found in 12 eyes (5%). Secondary IOP elevation was present in 64% of eyes with iris metastases, 67% with ciliary body metastases, and 1% with choroidal metastases. The most common mechanism of elevated IOP was tumor invasion of the angle in the case of iris and ciliary body metastases, and angle closure in the case of choroidal metastases. There were 303 eyes with retinoblastoma, 17% of which had elevated IOP which was secondary to iris neovascularization in 70% of cases and to an angle closure without neovascularization in 27%. Several other intraocular tumors including lymphoma, leukemia, medulloepithelioma, melanocytoma, and adenoma of the iris pigment epithelium were occasionally associated with secondary elevated IOP.