A chair comprising: - a base structure, - a seat fixed to the base structure, - a backrest, and - a pair of oscillation joints which connect the backrest to the seat or to the base structure so as to allow tilting of the backrest around a transverse axis between a rest position and a backwardly tilted position, wherein each of said oscillation joints comprises: - a rigid support having a first and a second arm (36, 38) essentially arranged according to an L shape, - an elastic device comprising a telescopic element including a first support body and a second support body having respective tubular portions (76, 82) connected together in a slidable manner by means of a guide shaft, and a helical compression spring arranged coaxially to said tubular portions (76, 82) of said telescopic element, wherein the elastic device is arranged within said first arm of the rigid support and wherein said first support body is articulated to said first arm of the rigid support, - a rigid lever articulated to said second arm of the rigid support around a transverse pin and having a first and a second lever arm (56, 58) located on opposite sides with respect to said transverse pin, wherein said second lever arm protrudes upwards from one end of said rigid support and is fixed to a corresponding side edge of the backrest and wherein said second support body of the elastic device is elastically pressed against one end of said first lever arm so that the elastic device applies an elastic force between said rigid support and said first lever arm, and wherein said rigid support has a first stop against which said lever rests in the rest position and a second stop against which said lever rests in the position of maximum backward tilt. - a base structure, - a seat fixed to the base structure, - a backrest, and - a pair of oscillation joints which connect the backrest to the seat or to the base structure so as to allow tilting of the backrest around a transverse axis between a rest position and a backwardly tilted position, - a rigid support having a first and a second arm (36, 38) essentially arranged according to an L shape, - an elastic device comprising a telescopic element including a first support body and a second support body having respective tubular portions (76, 82) connected together in a slidable manner by means of a guide shaft, and a helical compression spring arranged coaxially to said tubular portions (76, 82) of said telescopic element, wherein the elastic device is arranged within said first arm of the rigid support and wherein said first support body is articulated to said first arm of the rigid support, - a rigid lever articulated to said second arm of the rigid support around a transverse pin and having a first and a second lever arm (56, 58) located on opposite sides with respect to said transverse pin, wherein said second lever arm protrudes upwards from one end of said rigid support and is fixed to a corresponding side edge of the backrest and wherein said second support body of the elastic device is elastically pressed against one end of said first lever arm so that the elastic device applies an elastic force between said rigid support and said first lever arm, and wherein said rigid support has a first stop against which said lever rests in the rest position and a second stop against which said lever rests in the position of maximum backward tilt.