Lena Dunham & 'Girls' Co-Stars Rock Swimwear for 'Girls' Trailer - Watch Now!

Lena Dunham and Allison Williams jump into a pool in their bikinis with Jemima Kirke and Zosia Mamet in their one pieces in this brand new trailer for their show Girls.

Also appearing in the trailer is frequent guest star Andrew Rannells.

PHOTOS: Check out the latest pics of Lena Dunham

“I am not immune to pressures. Learning every day. Have a beautiful holiday. I know I need it.” Lena recently tweeted.

Girls is set to return to HBO on January 12 – be sure to check it out!

ARE YOU EXCITED for Girls to return to HBO???