Credit: London Entertainment/Splash News Online

Matthew McConaughey has lost one of his sexiest attributes: his full head of curly blonde hair!

The 42-year-old actor stepped out in Beverly Hills Tuesday wearing a baseball cap concealing his newly shaved head. McConaughey, who was dressed head-to-toe in J.K. Livin apparel, was all smiles before beginning his workout at L'Ermitage Hotel.

No word yet on why McConaughey ditched his signature hairstyle, as the actor was photographed with a full head of hair while shooting Thunder Run in L.A. Saturday.

McConaughey isn't the only star to shave his head in 2011: Jake Gyllenhaal and Matt Damon both lopped off their locks for film roles earlier this year.

Tell Us: Do you like Matthew McConaughey bald?