Classification of Transplant Rejection Hyperacute rejection(超急性排异反应) Occurs within minutes to a few hours after transplantation > Acute rejection(急性排异反应) Occurs within days, weeks, months even years. Chronic rejection(慢性排异反应) Occurs in months to yearsClassification of Transplant Rejection ➢Hyperacute Rejection(超急性排异反应) Occurs within minutes to a few hours after transplantation ➢Acute Rejection (急性排异反应) Occurs within days, weeks, months even years. ➢Chronic Rejection (慢性排异反应) Occurs in months to years