The present invention relates to methods for inhibiting the activity of human kallikrein 7 (KLK7) (also known as serine protease stratum corneum chymotryptic enzyme, SCCE). The invention further relates to the use of KLK7 inhibitors of Formula I for the treatment and prevention of diseases, more specifically for the treatment and prevention of skin diseases. The invention also provides new compounds demonstrated to be inhibitors of KLK7.