Marine-derived fungi surviving as symptomless endophytes in seaweeds and seagrasses were screened for production of xylan-degrading enzymes. Of the eight endophyte isolates obtained from five different seagrasses and another eight from six different marine algae, half of them exhibited xylanase activity in an agar plate assay. Further examination of these lead candidates using spectrophotometric assays revealed that Trichoderma harzianum, endophytic in the brown alga Sargassum wightii, had the maximum secreted xylanase and xylosidase activity. Moreover, this fungus could grow in NaCl-containing media (up to 1.2 M NaCl), and inclusion of 0.26 M NaCl in the media elicited a two- and three-fold increase in extracellular xylanase and xylosidase activity respectively. These findings highlight the potential of prospecting marinederived fungal endophytes to identify novel cell-wall degrading enzymes of value to the biofuel industry.