Endophytic fungi associated with leaves and stem tissues of Boswellia sacra growing in Dhofar Mountains of Oman were investigated from May 2008 through October 2011. The biological diversity, tissue-preference and seasonal variations of fungi were evaluated. Forty-three species and 3 varieties of fungi were recovered as new records from this plant. Of these isolates, 35 species are new reports to the mycoflora of Oman, whereas 12 species were added to the list of fungal flora of the Arabian Peninsula. The genus Alternaria (12 species) is the most prevalent genus recovered from 12.5-83.3% of the screened leaves and stem samples, followed by