The present invention relates to fungal serine protease variants, which comprise an amino acid substitution of valine at position 208 of the parent Fusarium equiseti Fe_RF6318 serine protease, wherein the position of the substitution corresponds to the amino acid sequence of the mature Fe_RF6318 enzyme defined in SEQ ID NO:2. The variants have improved thermal stability and/or detergent stability compared to the parent Fe_RF6318 enzyme. Preferably the substitution is V208I and more preferably the variants comprise additional amino acid changes which further increase the stability. Also disclosed are nucleic acid sequences encoding said protease variants as well as recombinant vectors and host cells for the production of the variants. The serine protease variants are applicable in laundry and dish-washing detergent compositions, in treating fibers, in treating wool, in treating hair, in treating leather, in treating food or feed, or in any application involving modification, degradation or removal of proteinaceous material.