Tacuarembó is a department located in northeastern Uruguay, whose population is the result of several migration waves from Europe and Near East, as well as Africans and Afro-descents mostly from Brazil; these waves settled with the territory's various Native ethnic groups (Charrúa, Minuán, and Guaraní). In the past, this population has been the focus of genetic studies showing this trihybrid origin, with greater contributions of Natives and Africans than in other Uruguayan regions. In this study we analyzed eight Alu insertions (A25, ACE, APOA1, B65, D1, F13B, PV92, TPA25) to provide valuable information for ancestrality and genetic differentiation and to compare with both previous studies on the Tacuarembó population and Alu frequencies in other Uruguayan populations. The European contribution to Alu and classical markers was almost equal to that of a previous study using 22 classical markers (63% vs. 65%), while African contribution was higher (30% vs. 15%), and Native American contribution shows an important difference in Alu: 7% versus 20%. We found no significant differences in genetic differentiation between Tacuarembó and Montevideo but significant differences between Tacuarembó and Basque descendants from Trinidad. Our results support previous findings obtained with classical markers that demonstrate the trihybrid composition of the Tacuarembó population, correlated with historical records. Thus, Alu insertions provide interesting information in light of the admixture process in the Uruguayan population.