An adjustable chair comprises chair support, backrest, a backrest support mechanism including at least one backrest arm pivotally connected to the support, and a seat having front and rear regions and a seat surface. The chair includes first and second seat support mechanisms with the first mechanism adjustably connecting the front region of the seat and the second mechanism adjustably connecting the rear region. The second seat support mechanism includes at least one seat arm having front and rear arm extensions and connected to the support for pivotal movement about a horizontal axis. The rear arm extension is pivotally connected to the rear region of the seat. A toggle arrangement is pivotally mounted on the chair support and engages the front end section of the at least one seat arm and front end section of the at least one backrest arm.