Seo Hyun Jin
- Name: Seo Hyun Jin (서현진)
- Birthdate: February 27, 1985
- Blood Type: B
- Height: 167cm
- Weight: 45kg
- Education: Korean Performing Arts (10 years)
Though Seo Hyun Jin had the least experience prior to debuting compared to her fellow M.I.L.K. members and was the youngest member, Seo quickly impressed many with her talent. She become the lead vocalist and also the strongest dancer of the group.
During the period after the promotion of M.I.L.K.'s first album and before the announcement of Bae Yumi's change of label, Seo was the group member who appeared most on the SM Town seasonal albums, participating until 2007 (appearing on the collective SM Town' songs for the first two albums). She also sang the Korean version of Every Little Thing's "Grip!" for the Korean broadcast of the Japanese anime Inuyasha.
After M.I.L.K. disbanded, Seo Hyun Jin remained relatively inactive until the end of 2005, when she landed a major role in the Seensee Musical Company's production The Sound of Music. In 2006 she participated on the OST of the popular drama Goong.
- [2003.06.23] 2003 Summer Vacation in SMTOWN.com (#2 Paradise (SM Town), #5 Summer in Dream (SM Town))
- [2004.06.29] 2004 Summer Vacation in SMTOWN.com (#1 Hot Mail <Yeoreum Pyeonji> (SM Town))
- [2006.01.25] Goong OST (#4 Give me a little try)
- [2006.06.21] '06 SUMMER SMTOWN (#8 Raindrops)
- [2006.11.02] Hyena OST (#4 0 (Yeong))
- [2006.12.12] 2006 Winter SMTOWN (#11 Nunui Iyagi)
- [2007.05.23] Air City OST (#5 Calling)
- [2007.12.07] 2007 WINTER SMTOWN (#8 Have Yourself A Merry Little Christmas)
-  Love Me Not
-  Dating on Earth
-  Story of Wine
-  The Madonna (Short Film)
-  Shame
-  Magic