In Yemen, agriculture are economically very important, especially for local consumption as fresh fruits and vegetables or for industrial products and exportation purpose. Fruits are widely cultivated in different Yemeni provinces, which include (cold and hot areas). The biodiversity of fungi associated with post-harvest decay of apple, orange, banana, mango and grape fruits was studied. Production of extracellular cell-wall degrading enzymes and mycotoxins by the isolated fungi both in vitro and in vivo was also investigated.