Technical Abstract: Six oat genotypes were grown in nursery yield trials during 1989-1992 at Lisbon, ND. Groats were analyzed for soluble and insoluble dietary fiber content and composition. Genotype-by-growing year interaction was not significant for soluble or insoluble dietary fiber. Soluble and insoluble dietary fiber differed with genotype (6.0-7.1% and 4.1-4.9%, respectively). The genotype-by-growing year interaction was significant for soluble beta-glucan content but not for total neutral sugar or uronic acid content of the soluble dietary fiber. Genotypes did vary in total neutral sugar content but not in uronic acid content. The genotype-by-growing year interaction was not significant for total neutral sugar, beta-glucan, uronic acid, or Klason lignin content of insoluble dietary fiber. Genotypes did vary in total neutral sugar, beta-glucan, and Klason lignin content but not in uronic acid content of insoluble dietary fiber. The neutral sugar content of soluble dietary fiber was composed of glucose, arabinose, xylose, and galactose. The neutral sugar content of insoluble fiber was composed of glucose, arabinose, and xylose. The content and composition of soluble and insoluble dietary fiber varied with oat genotype. Therefore, oat genotypes could be bred for specific dietary fiber content and composition.