Yes you can, Medisave is usable for immediate family including parents, spouse, children and grandparents. Went through this when my mum was warded. Key things: there are withdrawal limits per day of hospitalisation and per procedure (the Medisave Withdrawal Limits), so it usually won't cover the entire bill, it covers a chunk. First check if your dad has MediShield Life or an Integrated Shield Plan, that should be the primary payer for the ward and surgery, then Medisave (his first, then yours) covers the co-payment and deductible portions. At the hospital, tell the billing counter you want to use your Medisave for your father, they'll get you to authorise it. Also ask if he qualifies for any subsidy or MediFund if the balance is still tough. Don't panic, the safety nets stack.