Veteran comedian Billy Crystal is to write a new book about ageing.

The When Harry Met Sally star, 64, has signed a deal with publishing firm Henry Holt and Company to detail his own experiences with getting older.

Joking to the Associated Press, he says, "There are 77 million of us baby boomers in the country (America) and this book will speak to them and how we look at the world."

And he already has big plans for the currently-untitled tome - Crystal tells the publication he's considering adapting the work for the stage.

Crystal is aiming to release the book in time for his 65th birthday in March, 2013.