Abstract. Given a vector a ∈ R n , we provide an alternative and direct proof for the formula of the volume of sections ∆ ∩ {x : a T x <= t} and slices ∆ ∩ {x : a T x = t}, t ∈ R, of the simplex ∆. For slices the formula has already been derived but as a byproduct of the construction of univariate B-Splines. One goal of the paper is to also show how simple and powerful can be the Laplace transform technique to derive closed form expression for some multivariate integrals. It also complements some previous results obtained for the hypercube [0,1] n .