An organ perfusion apparatus and method monitor, sustain and/or restore viability of organs and preserve organs for storage and/or transport. Other apparatus include an organ transporter, an organ cassette and an organ diagnostic device. The method includes perfusing the organ at hypothermic and/or normothermic temperatures. The methods further include perfusing the organ at hypothermic and/or normothermic temperatures with a second perfusate containing a substance for reacting with the organ. Condition of the organ may be automatically monitored, and the perfusion process can be automatically controlled using a control program.