The invention relates to a fireplace comprising a firebox (1) and a trough-shaped grate (3) including an upper end (4) and a lower end (5) and a wall construction (6 to 9), which comprises walls (6, 7) / wall portions at an acute angle ( alpha ) in relation to one another, the walls/wall portions being provided with elongated apertures (10) for supplying combustion air through the grate, the main direction of the apertures being at a 40 degree angle at the most in respect of an imaginary line (L) on the wall (6, 7) /wall portion, in which the apertures are formed, said line extending at a right angle in relation to a level defined by the upper end (4, 4') of the grate. In order for the grate to improve fine combustion and to enable low-emission combustion throughout almost the entire combustion process, the apertures (10) examined together form in the portion of the walls (6, 7) /wall portions, in which they are formed and which is closer to the lower end (5) of the grate, a larger surface area than in the portion of the walls/wall portions, which is closer to the upper end (4) of the grate. The invention also relates to a grate.