Abstract the objective of this work was to select black oat genotypes using the mgidi for simultaneous selection, comparing it with the smith-hazel index. The experiment was carried out in frederico westphalen/rs and pato branco/pr, in a randomized block design, with three replications, with 9 genotypes tested. Days from emergence to flowering and maturation; cutting and plant height; number of tillers; panicle length; tiller, plant, panicle, panicle seed mass, green and dry; and seed yield were obtained. Mgidi selected the genotypes ufsmfw 2-01 and ufsmfw 2-04 for frederico westphalen and ufsmfw 2-07 and ufsmfw 2-04 for pato branco, which varied compared to the smith-hazel index in both environments. Mgidi was efficient in selecting the best black oat genotypes, showing desirable selection gains for most traits.