Abstract: This paper study uniqueness of differential polynomials of meromorphic functions sharing 1 IM. Let f(z)and g(z)be two non-constant meromorphic functions, whose zeros and poles are of multiplicities at least s, where s is a positive integer. Let n≥2 be an integer satisfying(n+1)s≥24. If f ⁿf ' and gⁿg' share the value 1 IM, then either f(z)=tg(z)for some(n+1)-th root of unity t or g(z)=c1e^cz, f(z)=c2e^-cz, where c1,c2, c are constants satisfying(c1c2)ⁿ⁺1c2=-1.

Key words: differential polynomial, uniqueness, meromorphic function, sharing value