The Shalit family allowed Israeli media outlets on Tuesday to publish the letter, handed over to Israel by Egyptian mediators four months after the soldier was captured in a cross-border raid in June 2006.
The letter reads, in part, "I send you peace and health. My own health is dwindling from day to day, particularly my mental health, and this causes me much depression."
"I am waiting for this intolerable nightmare of mine to end, to be released from this lonely and closed prison, especially since my 20th birthday has passed, one I had hoped we could celebrate together."
Shalit's father, Noam, said Tuesday that the release of the letter from three years ago was not a sign of anything regarding his son's current condition or negotiations to free him.