A tilt mechanism for a chair, configured to effect a coordinated movement of a chair seat and chair back, said tilt mechanism (10; 40) comprising: a base (11; 41) configured to be coupled to a chair base assembly, a back bracket (12, 12'; 42, 42') comprising a back attaching portion (23; 53) configured to be attached to said chair back and a pivot coupling portion (24; 54), a coupling arrangement (16, 25; 46, 55) configured to couple said back bracket (12, 12'; 42, 42') to said base (11; 41), said coupling arrangement (16, 25; 46, 55) comprising a guide track (25; 55) formed to have at least one channel (26; 56) and at least one guide member (16, 46) configured to be displaceably supported in said at least one channel (26; 56), one of said guide track (25; 55) and said at least one guide member (16, 46) being provided on said back bracket (12, 12'; 42, 42'), and the other one of said guide track (25; 55) and said at least one guide member (16, 46) being provided on said base (11; 41), said tilt mechanism being configured such that, when said coupling arrangement (16, 25; 46, 55) couples said back bracket (12, 12'; 42, 42') to said base (11; 41), pivoting said back bracket (12, 12'; 42, 42') about said pivot coupling portion (24; 54) causes said guide member (16, 46) and said guide track (25; 55) to be displaced relative to each other, effecting a displacement of said pivot coupling portion (24; 54) relative to said base (11; 41), characterized in that said pivot coupling portion (24; 54) of said back bracket (12, 12'; 42, 42') is configured to pivotably couple said back bracket (12, 12'; 42, 42') to said chair seat such that said back bracket (12, 12'; 42, 42') is pivoted about said pivot coupling portion (24; 54) when said chair back pivots, and the one of said guide track (25; 55) and said at least one guide member (16, 46) provided on said back bracket (12, 12'; 42, 42') is formed on said back bracket (12, 12'; 42, 42') at an intermediate location between said back attaching portion (23; 53) and said pivot coupling portion (24; 54). a base (11; 41) configured to be coupled to a chair base assembly, a back bracket (12, 12'; 42, 42') comprising a back attaching portion (23; 53) configured to be attached to said chair back and a pivot coupling portion (24; 54), a coupling arrangement (16, 25; 46, 55) configured to couple said back bracket (12, 12'; 42, 42') to said base (11; 41), said coupling arrangement (16, 25; 46, 55) comprising a guide track (25; 55) formed to have at least one channel (26; 56) and at least one guide member (16, 46) configured to be displaceably supported in said at least one channel (26; 56), one of said guide track (25; 55) and said at least one guide member (16, 46) being provided on said back bracket (12, 12'; 42, 42'), and the other one of said guide track (25; 55) and said at least one guide member (16, 46) being provided on said base (11; 41), said tilt mechanism being configured such that, when said coupling arrangement (16, 25; 46, 55) couples said back bracket (12, 12'; 42, 42') to said base (11; 41), pivoting said back bracket (12, 12'; 42, 42') about said pivot coupling portion (24; 54) causes said guide member (16, 46) and said guide track (25; 55) to be displaced relative to each other, effecting a displacement of said pivot coupling portion (24; 54) relative to said base (11; 41), characterized in that said pivot coupling portion (24; 54) of said back bracket (12, 12'; 42, 42') is configured to pivotably couple said back bracket (12, 12'; 42, 42') to said chair seat such that said back bracket (12, 12'; 42, 42') is pivoted about said pivot coupling portion (24; 54) when said chair back pivots, and the one of said guide track (25; 55) and said at least one guide member (16, 46) provided on said back bracket (12, 12'; 42, 42') is formed on said back bracket (12, 12'; 42, 42') at an intermediate location between said back attaching portion (23; 53) and said pivot coupling portion (24; 54).