Pastures assume a prominent position in the Brazilian agricultural scenario, covering about three quarters of the cultivated area nationwide. In addition to the physical aspect, pastures are the main feeding source for the Brazilian herd. Pastures account for almost 90% of the beef consumed in Brazil and for most of the 21 billion liters of milk produced annually in the country. It is estimated today that in Brazil grasses of the genus Brachiaria are cultivated in approximately 84 million hectares. In spite of its importance for the national dairy industry, the amount of information on this genus is rather limited, especially for genetic improvement. In Brazil, the most cultivated species of Brachiaria are B. decumbens, B. brizantha, B. humidicola and B. ruziziensis. With the increase in the interaction between agriculture and livestock, the demand for B. ruziziensis seeds has increased. In addition, B. ruziziensis is the only diploid and sexually propagated species of the genus cultivated in Brazil, thus being the source for crossbreeding and increase in variability to aid subsequent work on genetic improvement. Based on the above, this project aimed to carry out basic studies on Brachiaria ruziziensis in order to obtain information for implementing an intrapopulation recurrent selection program in this species. In that regard, efforts were directed towards evaluating the forage potential of half-sib families of B. ruziziensis; obtaining estimates of genetic parameters of these families; verification of variability among families for tolerance to toxic aluminum; determination of germination percentage and seedling vigor; and molecular characterization of the best selected families. In each State of Brazil with the greatest use of B. ruziziensis, 100 plants were collected, which were cultivated with spacing of 1 m between plants and 1.5 m between rows. Seeds harvested from each of these plants made up half-sib families and were evaluated in field and laboratory experiments. The results showed the existence of genetic variability for different traits of importance for increasing the quantity and quality of forage produced by the species. The averaged forage dry matter productivity of the best families exceeded the average of the controls by 100%, in the cuts carried out during the rainy season. The best selected families were intercrossed to obtain an improved population of B. ruziziensis, initiating a recurrent selection program for the species. The results of this study were extremely important for national livestock, enabling the expansion of the genetic base of the species, exploration and generation of variability for the improvement and consequent reduction of the genetic vulnerability of Brazilian pastures.