The aim of this study was to define effects of processing on dietary fiber (insoluble and soluble fraction) and β-glucan contents in barley and oat grain. The material was whole grain of barley (naked cv. Rastik, covered cv. Start) and oats (naked cv. Akt, covered cv. Kasztan) and their milling fractions: flour and bran. In addition germinated grain of both species was analysed. It was found that whole barley and oat grain were comparable sources of dietary fiber and β-glucans. Their contents of dietary fiber and β-glucans were (%d.m.): barley cv. Rastik – 21,6 and 4,2%, barley cv. Start – 26,3 and 3,9%, oats cv. Akt – 22,2 and 4,3%, oats cv. Kasztan – 25,4 and 4,1% , respectively. The barley flour obtained from the whole grain of cv. Rastik and cv. Start showed higher content of β-glucans (%d.m.: 2,8 and 4,1%) than the oat flour obtained from cv. Akt and cv. Kasztan (%d.m.: 1,3 and 1,4%). The fraction of β-glucans was more uniformly distributed in barley kernels. The content of total dietary fiber in bran of barley cultivars was (%d.m.): cv. Rastik – 23,6 and cv. Start – 24,7%. In bran fraction of oat cultivars, the content of total dietary fibre was (%d.m.): cv. Akt – 24,9 and cv. Kasztan 25,7%. The bran obtained from covered cultivars of barley and oat (cv. Start and cv. Kasztan) showed high contribution of β-glucans (%d.m.): 5,3 and 6,2%. Likewise, β-glucan concentration in bran of naked forms of barley and oat was high (%d.m.): cv. R a s tik -4,5 and cv. Akt – 4,7%. The content of total dietary fiber (%d.m.) in the whole grain of barley and oats was not affected by germination (cv. Rastik – 21,8%, cv. Start – 26,7% and cv. Akt – 20,6%, Kasztan – 24,9%). In contrast, the germination decreased the content of β-glucans in these cultivars (%d.m.): from 4,2 to 3,8, from 3,9 to 2,9, from 4,3 to 2,8, and from 4,1 to 2,7%, respectively.