Abstract: A multi adjustable chair is comprised of a support frame to which is secured an adjustable seat assembly and an adjustable backrest assembly. The backrest assembly has displaceable back support plates that are adjustable to a desired position. A back cushion is secured over back support elements and is displaceable in unison therewith as the backrest is extended or retracted. The seat assembly has a pair of laterally displaceable seat panels as well as a front guide frame and the seat cushion is also extendable both laterally and forwardly as the seat panels and front guide frame are displaced to adjust the size of the seat assembly. The adjustable chair is preferably, but not exclusively, a wheelchair and it is provided with an adjustable support base assembly and a chair tilting mechanism.