| SIK | |
| Location Country: | Greenland |
| Affiliation: | NFS |
| Members: | More than 10.000 (2010) |
| Full Name: | National Confederation of Trade Unions of Greenland |
| Native Name: | Sulinermik Inuussutissarsiuteqartut Kattuffiat |
| Founded: | 2 July 1956 |
| Headquarters: | Nuuk, Greenland |
| Key People: | President Jess G. Berthelsen |
| Website: | sik.gl in English |
The National Confederation of Trade Unions of Greenland (Greenlandic: Sulinermik Inuussutissarsiuteqartut Kattuffiat or simply SIK) is a trade union centre in Greenland. It was formed in 1956 as 'GAS, Grønlands Arbejder Sammenslutning" until 1978 and has a membership more than 10,000, approximately 40 % of the Greenlandic workforce.
SIK is affiliated with the Council of Nordic Trade Unions.
1956: Lars Svendsen
1961: Kaj Johnsen
1963: Ôdâq Olsen
1972: Ulf Olsen
1973: Ôdâq Olsen
1978: Abraham Mikaelsen
1978: Ôdâq Olsen
1980: Jens Lyberth
1987: Finn Heilmann (May-October)
1987: Jonas Fleischer (March)
1987: Jens Johansen (March)
1988: Ole Magnussen
1989: Kristian "Pablo" Poulsen
1990: Jess G. Berthelsen