EN
By getting uniformly asymptotic estimates for the Poisson kernel on Heisenberg groups $ℍ_{2n+1}$, we prove that there exists a constant A > 0, independent of n ∈ ℕ*, such that for all $f ∈ L¹(ℍ_{2n+1})$, we have $||Mf||_{L^{1,∞}} ≤ An||f||₁$, where M denotes the centered Hardy-Littlewood maximal function defined by the Carnot-Carathéodory distance or by the Korányi norm.