An adjustable backrest assembly for a materials handling vehicle. The backrest assembly includes an adjustable backrest structure and mounting structure for mounting the adjustable backrest structure on the materials handling vehicle so that the adjustable backrest structure extends generally vertically over load handling apparatus of the materials handling vehicle. The mounting structure enables pivoting movement of the adjustable backrest structure from a first position generally adjacent a power unit of the materials handling vehicle wherein pallets of a first size are accommodated to at least a second position spaced along the load handling apparatus from the power unit wherein pallets of a second size are accommodated.