A collapsible splint includes an expandable frame within a flexible generally rectangular sleeve. The expandable frame includes a number of members that are extendable rods or tubes. The members are oriented longitudinally within the sleeve and arranged transversely across the sleeve and adjacent to one another. The rods are secured at one end of the sleeve and are connected to one another by transverse links to form the frame. The sleeve includes an opening through which the frame can be accessed and extended to a desired length. The sleeve also includes straps on its rear side suitable for binding the collapsible splint around a fractured limb.