Over the past two decades, there has been an increasing interest in the study of endophytes, their origin, biodiversity, the interactions between endophytes and host plants, the role of endophytes in ecology, as well as the chemical properties and biological activity of secondary metabolites produced by them. In this research endophytic fungi from twigs and branches of oak in Hatam-baig and Kalibar regions were identified based on molecular and morphological characteristics. Towards this aim, samples were collected from twigs and branches of oak trees in above-mentioned regions during June and September 2014. Pure cultures were established using a single spore or hyphal tip techniques. The identity of fungal isolates was determined based on morphological characteristics and sequence data from ITS-rDNA and Tub region. In this study 25 fungal species including Alternaria alternata species complex, Arthrinium arundinis, Aspergillus flavus, Bipolaris spicifera, Biscogniauxia mediterranea, Chaetomium globosum, Clonostachys rosea, Cladosporium cladosporioides, Daldinia vernicosa, Daldinia palmensis, Daldinia loculata, Discula quercina, Epicoccum nigrum, Fusarium oxysporum, Fusarium proliferatum, Fusarium solani, Nigrospora oryzae, Ochrocladosporium elatum, Paecilomyces formosus, Penicillium commune, Penicillium spinulosum, Pyronema domesticum, Sordaria fimicola, Sordaria sibutii and Trichothecium roseum were identified as endophytic fungi inhabiting twigs and branches of oak trees in Hatam-baig and Kalibar region. The majority of the species that were identified in this study, are reported for the first time from Quercus macranthera. The assemblage of endophytic fungi in healthy tissues of oak trees might indicate that some of the fungi as possible latent pathogens of oak.