Persian oak (Quercus branti Lindl) is the most important forest tree of the Zagros mountains. During the recent drought conditions, the oak decline has widely been observed in the areas of Chaharmahal and Bakhtiari Province, especially the town Lordegan. Symptoms include early fall coloration, early leaf drop, vascular discoloration in the twigs (Fig. A-1), drying of the branches, discoloration of the main trunk and branches, cracks and splitting of the trunk, the presence fungal organs as black and olive powdery under the bark (Fig. B-1) and death of the trees. While up to 70% of the trees may suffer from the disease on south-facing slopes (Fig. D-1), north-facing slopes are normally unaffected(Fig. C-1). In 2018, samples of bark, main trunk, and a branch of trees with symptoms (16 specimens) and some specimens (7 specimens) of apparently healthy trees were collected in Lordegan town and isolated by standard methods of isolation of pathogenic fungi on malt agar and potato-dextrose-agar media. The fungal isolates were purified after growth and sent to Botany Research Department of Iranian Research Institute of Plant Protection for identification. Identification results showed that isolates of Biscogniauxia Mediterranea, Paecilomyces cf variotii and Paraconiothyrium sp. are fungi associated with charcoal rot and oak decay in Chaharmahal va Bakhtiari province. From 16 samples with described symptoms, 9 samples of Paraconiothyrium sp, 5 samples of B. mediterranea and 4 samples of Paecilomyces cf variotii were isolated. Two samples of asymptomatic samples were also isolated Paraconiothyrium sp and B. mediterranea.