A plate-agar technique for fungal screening was applied to evaluate the xylanolytic activities of 18 Penicillium janthinellum and 10 Aspergillus sydowi species from the Amazon region. In order to compare these genera with those of other regions, one Aspergillus sp., one P. janthinellum, and 12 unknown genera from the southern region of Chile were studied. From these fungi strain, A. sydowi (56 strain) (25.2 IU/mL), P. janthinellum (671 strain) (47.3 IU/mL) from Amazonia, P. janthinellum (X4Z2 strain) (9.5 IU/mL), and an Aspergillus sp. (X2M1 strain) (33.3 IU/mL) from the southern region of Chile were identified.