The purpose of this paper is to study finite-dimensional irreducible representations of the quantum loop algebra U ε = U ε ( g) at an odd root of unity ε. Here g is a simple finite-dimensional Lie algebra over C and g = C[t, t −1 ] ⊗ C g is the associated loop algebra.Denoting by Spec R the set of all finite-dimensional irreducible complex representations of an associative algebra R over C and by Z the center of R, we have (by Schur's lemma) the canonical map:(Recall that the value of χ on a representation σ ∈ Spec R is defined by σ(z) = χ(σ)I for z ∈ Z.) If R is a finitely generated module over Z (which is the case for R = U ε (g) [DC-K]) one knows that the map χ is surjective with finite fibers and, moreover, it is bijective over a Zariski open dense subset of Spec Z. In other words, at least "generically", Spec Z parametrizes the set of all irreducible finitedimensional irreducible representations of R. This well-known observation was the starting point for a thorough (albeit incomplete) study of Spec U ε (g) taken up in [DC-K], [DC-K-P1,2,3] and other papers. In the case when R = U ε the situation is quite different since U ε is not finitely generated over its center Z = Z ε . The canonical map χ is not surjective and is not generically bijective. The main result of the present paper is the calculation of the image of χ in Spec Z ε .The first result (Proposition 2.3) provides a (infinite) set of generators of the algebra Z ε . By general principles, Z ε has a canonical structure of a Poisson algebra. Furthermore, we show that Z ε is a Hopf subalgebra of the Hopf algebra U ε . (Recall that this isn't the case for U ε (g).) Thus, Z ε is a Poisson Hopf algebra, and using a "Frobenius homomorphism" we obtain that it is isomorphic to a certain Poisson Hopf algebra U 1 independent of the odd root of unity ε (Corollaries 3.2.1 and 3.2.2).In the dual language, Spec Z ε is a Poisson proalgebraic group. Our first key result (Theorem 5.3) is the construction of a Poisson group isomorphism (0.2) π : Spec Z ε → Ω