We analyzed data obtained prospectively on 48 consecutive patients treated with intravitreal silicone oil. Forty percent were diabetic. Follow-up ranged from three to eight months. An increase in intraocular pressure (IOP) (defined as a rise 10 mmHg above the preoperative level) developed in 56% of the eyes in the postoperative period (range, 10 to 53.4 mmHg; mean rise, 21.63 mmHg). There was no significant difference in mean pressure rise between diabetic and non-diabetic eyes. The increase in IOP was transient in 78% of the patients. In 70% the IOP rose to a level greater than 22 mmHg. All of these patients required medical treatment, and some silicone oil was removed in six. Only 22% of those requiring treatment still received medication at follow-up. No patient in this series had uncontrolled IOP.