Dedicated to Ivo Babuška on the occasion of his 80th birthday.Abstract. We prove a regularity result for the Poisson problem −∆u = f , u| ∂P = g on a polyhedral domain P ⊂ R 3 using the Babuška-Kondratiev spaces K m a (P). These are weighted Sobolev spaces in which the weight is given by the distance to the set of edges [4,33]. In particular, we show that there is no loss of K m a -regularity for solutions of strongly elliptic systems with smooth coefficients. We also establish a "trace theorem" for the restriction to the boundary of the functions in K m a (P).