Let R be a nil ring. We prove that primitive ideals in the polynomial ring R [x] in one indeterminate over R are of the form I[x] for some ideals I of R.All considered rings are associative but not necessarily have identities. Köthe's conjecture states that a ring without nil ideals has no one-sided nil ideals. It is equivalent [4] It is known that if a polynomial ring R[x] is primitive then R need not be primitive [3] ( see also Bergman's example in [5]). Let R be a prime ring and I a nonzero ideal of R. Then R is a primitive ring if and only if I is a primitive ring [6]. Since the Hodges example has a nonzero Jacobson radical it follows that polynomial rings over Jacobson radical rings can be right and left primitive (see also Theorem 3).We recall some definitions afterA right ideal of a ring R is called modular in R if and only if there exists an element b ∈ R such that a − ba ∈ Q for every a ∈ R. If Q is a modular maximal right ideal of R then for every r / ∈ Q, rR + Q = R. An ideal P of a ring R is right primitive in R if and only if there exists a modular maximal right ideal Q of R such that P is the maximal ideal contained in Q.In this paper R[x] denote the polynomial ring in one indeterminate over R. Given polynomial g ∈ R[x] by deg(g) we denote the degree of R, i.e., the 1