The present invention relates to a method for genetically modifying a filamentous fungus host for improved protein production. The method comprises that a filamentous fungus host is genetically modified to overexpress or to be deficient of specific genes. The invention relates also to the modified hosts. Furthermore, the invention relates to a method for improved production or for producing an improved composition of proteins, such as cellulases, hemicellulases, other proteins involved in the degradation of lignocellulosic material, or other proteins, in a filamentous fungus host.
