SIOP

SIOP may refer to:
 * International Society of Paediatric Oncology
 * Sales Inventory Operations Planning, an integrated business management process
 * Sheltered Instruction Observation Protocol, a research-based observation instrument used to measure sheltered instruction
 * Single Integrated Operational Plan, the tactical blueprint for the deployment of nuclear weapons by the United States
 * Society for Industrial and Organizational Psychology, a division of the American Psychological Association for I/O psychologists
 * Steroid-induced osteoporosis, a bone disease that leads to an increased risk of fracture