Seinfeld star Jason Alexander is sporting a full head of hair after undergoing treatment to combat baldness.

The actor, 52, spent the summer trying new treatments to reverse his longterm thinning hair problem, and he admits the process has been successful.

In a post on Twitter.com, he writes, "I am experimenting with some interesting hair systems. Don't be shocked if you suddenly see pics of me with more hair than usual."

Alexander sported his new look at the Casting Society of America's 27th Annual Artios Awards ceremony in New York on Monday.