The Denomination of Origin for Idiazabal cheese was created in 1987 and defines the basic regulations for the product's manufacture.

also stipulates that the milk be curdled with the natural lamb rennet, and permits external smoking of the cheese.

Recently some Basque Country farmers have begun to use hybrid Assaf sheep, which some maintain does not meet the Denomination of Origin for the cheese.

The milk coagulates at a temperature of 25 to 35 °C (77 to 95 °F), with the addition of natural lamb curd, resulting in a compact curdle after 30 to 45 minutes.

The optional smoking takes place at the end of the aging process, using woods from the beech-tree, birch-tree, cherry tree or white pine.

The interior is compact, without air pockets or with only pin-head size holes, and is beige or pale yellow in color.

The taste is strong and pronounced, slightly acidic and piquant, buttery and consistent, with a characteristic sheep milk flavor.