This paper investigates the patterns of cognate objects (COs) associated with unergatives and unaccusatives in Sason Arabic. We propose that COs of both unergatives and unaccusatives are not true arguments, as evinced by their highly productive and unrestricted use, but constitute rhematic complements in the sense of Ramchand (2008), therefore cannot be used as diagnostics for unergative-unaccusative distinction in the language.