[en] We have studied the thermopower of U doped CeAl₂ and Ce and La doped UAl₂. Despite different ground state properties of CeAl₂ and UAl₂, the former being an antiferromagnetic heavy-fermion compound and the latter non-magnetic, we have found that not only thermopower data for pure CeAl₂ and UAl₂ are similar but also the thermopower results of doped samples behave similarly. Although the similarity seen in pure systems is yet to be understood, we interpret the doping effects as the results of changes in energy dependent relaxation time with doping. (author)