3I

3I or 3-I may refer to:


 * Iniziative Industriali Italiane
 * 3I Sky Arrow
 * 3i London-based private equity and venture capital company
 * 3-I League, see Illinois–Indiana–Iowa League
 * 3i Infrastructure, an investment business headquartered in Jersey
 * 3i Infotech Limited, an Indian IT company
 * ESX Server 3i, a version of VMware ESX