Over half of Canadians support sharing their health data to improve care, research, and early detection—if it's safe and transparent. Most (60%) want to give consent before data is used. Key conditions include knowing how data is used, who sees it, and that it's securely stored. Support is stronger for public use (like rare disease alerts) than for private companies. Many (56%) want to be asked every time their data is used. Trust and control are key to public support for secondary data use in Canada.