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 apparatus and methods include the organ cassette with one or more openings configured to allow tubing to pass through the openings and be connected to the organ or tissue within the cassette, and including a pressure control device to allow pressure inside the portable housing to be varied.