Seoul International Eco Film Festival (previously known as Green Film Festival in Seoul) (SIEFF), held in Seoul, South Korea, is the largest international environment film festival in Asia.

Established in 2004, it is an annual event held in time with World Environment Day – June 5.

GFFIS of 2014 was held from 9th to 15 May, every day from 11:00 to 18:00 at the Seoul Museum of History, Cinecube and INDIESPACE, Gwanghwamun.

[2] The 18th edition of the film festival was held from June 3 to June 9, 2021, at the Rachel Carson Hall of the Korea Green Foundation with no on-site audience.

With the expansion of the film festival this year's slogan has been kept as 'Ecoverse'.