O presente trabalho se refere ao estudo da variação genética de 16 populações de Ilex paraguariensis St. Hil, em dois locais no estado de Santa Catarina. O delineamento utilizado na implantação dos ensaios foi o látice balanceado 4 × 4, com 5 repetições. A parcela foi constituída de 25(5×5) plantas, com espaçamento entre plantas de 4 × 3 metros. Os resultados mostraram que a proporção entre as plantas masculinas e femininas ficou próximo a 1:1. As populações apresentaram variações genéticas altamente significativas para todas as características estudadas em ambos os locais, com exceção da altura de plantas aos 71 meses de idade, no ensaio de Chapecó-SC. A análise conjunta para locais, mostrou uma diminuição gradual na significância com o aumento da idade, não apresentando diferença significativa para nenhuma característica aos 71 meses de idade. As populações que apresentaram maior potencial para melhoramento, em ambos os locais, são as de Água Doce-SC, Barão de Cotegipe-RS e Ilópolis-RS. As populações mais indicadas para plantio são as de Água Doce-SC, Passo Fundo-RS e Venâncio Aires-RS, em ambos os locais

The genetical variation of 16 populations of Ilex paraguariensis St. Hil., with 15 representative native populations of the occurrence area of the species and a commercial material tester was studied. Two trials were set up in Chapecó, in western state of Santa Catarina, and in Três Barras, in the northern state. A balanced 4 x 4 lattice design with 5 replications was used. The plot included 25 (5 x 5) plants with 4 x 3 meter spacing between plants. Survival characteristics, crown diameter, height, leaf density, and fructification were evaluated. The results obtained for fructification were similar for both sites, with sex ratio ranging 1 : 1. A great variation in the percentage of fructification between the populations within the sites was observed and only the population of Quedas do Iguaçú-PR presented presented significant change concerning sex ratio. The populations presented highly significant genetical variations for all characteristics in both sites, except for plant height at 71 months of age in the Chapecó-SC trial. The analysis of both sites showed a gradual decrease in interaction significance per site with age increase, with no significant change observed for any of the characteristics at 71 months of age, which shows a similar behavior of populations in both sites. The correlations among survival, crown diameter and height in different ages obtained by the Pearson's correlation coefficient were all high and significant, thus showing that the results at 2 years of age may be extrapolated for advanced ages within the same site. Low correlations obtained before and after pruning show the need of the selection for a supplementation with second ratoon evaluations after pruning. The populations presenting higher breeding potential in both sites are those of Água Doce-SC, Barão de Cotegipe-RS and Ilópolis-RS. The Água Doce-SC, Passo Fundo-RS and Venâncio Aires-RS populations are the best indicated for planting in both sites