- "Girlfriends" is based on a novel by Lee Hong which won the 31st Today's Writer Award. The movie adaption was written by No Hye Young (prior writing credits include "Singles,"Please Teach Me English," & 200 Pounds Beauty").
- Filming started August 22nd, 2009.
- Cast and crew gave Kang Hye Jung a surprise party on the set of "Girlfriends" on September 5th, 2009. The surprise party was to celebrate Kang Hye Jung's upcoming wedding to singer "Tablo" and her 5 week pregnancy.
Song-i (Kang Hye Jung : Rules of Dating, Welcome to Dongmakgol) starts dating her handsome co-worker Jin-ho (Bae Soo Bin : Temptation of an Angel , Brilliant Legacy , Dong Yi ). But when she suspects Jin-ho might be cheating on her, she sets out to meet the ``other woman,'' only to learn that he has not one, but two, other ``girlfriends'': Jin (Han Chae Young : The Divine Hero , Only You , Sassy Girl Chun Hyang), Jin-ho's first love, is a sexy and successful party planner, while Bo-ra ( Heo Yi Jae : Prince S ), is a fearless, young college student. Strangely enough, Song-i finds that their similar taste in men to be the basis for a great friendship.