Abstract. The Fekete polynomials are defined as is the Legendre symbol. These polynomials arise in a number of contexts in analysis and number theory. For example, after cyclic permutation they provide sequences with smallest known L 4 norm out of the polynomials with ±1 coefficients.The main purpose of this paper is to prove the following extremal property that characterizes the Fekete polynomials by their size at roots of unity.then N must be an odd prime and f (x) is ±Fq(x).This result also gives a partial answer to a problem of Harvey Cohn on character sums.