In this paper, corn stalk as an agricultural residue was mixed with oak wood fiber to produce medium density fiberboards (MDF). Urea formaldehyde resin was used as binder. Hygroscopic and mechanical properties were evaluated according to the commercial standards in MDF production. Partial substitution of wood fiber with corn stalks fiber negatively affected all board properties. However, the mechanical properties fulfill the minimum requirements of the relevant standards such as TS-EN 310, 1999 and TS-EN 319, 1999. In some cases, they exceeded the standards, even with partial blending of corn stalk fibers.