Age limits for organ donation no longer exist. However, the general age limit for tissue donation is 70. Organs may be
donated from someone as young as a newborn.

Nearly everyone who wants to be a donor can donate at least tissues, if not organs as well. Do not assume that you are not healthy enough to donate; medical staff will do testing at the time of death to make that determination. The public service announcement at
http://www.shareyourlife.org/flash_detect.html puts it well: