Let k be a field with positive characteristic p > 0 and let G/k be a simply
connected semisimple group. We prove the following conjecture of Tits. If
[k : k(p)] less than or equal to p, then any subgroup U of G(k) consisting
of unipotent elements is contained in the unipotent radical of a k-paraboli
c subgroup of G. (C) Academie des Sciences/Elsevier, Paris.