In 2022 spring season, canker symptoms were observed on about 5% of pistachio (Pistacia vera L. cv. Siirt) trees in a 25 decares commercial orchard in Adıyaman province (37°30’24.0"N, 38°13’47.9"E), Turkey. Diseased trees showed symptoms of yellowing, branch and scaffold dieback, dark wood discoloration and stem canker. Infected wood tissues of four trees were surface sterilized in 1% sodium hypochlorite for 2 min, placed onto potato dextrose agar (PDA) and incubated in dark at 23 °C. All pieces of diseased trees consistently developed the same fungal colonies, morphologically similar to Fusarium spp. Cultures showed a white to dark purple in colour, macroconidia (3.8 to 4.9 × 27.7 to 39.8 μm) were thin-walled, slender, relatively straight, with 3 to 5 septate, and microconidia (2.7 to 3.6 × 5.4 to 8.2) were abundant, single celled, club shaped, and formed in chains and false heads from monophialides and polyphialides. Chlamydospores were absent. The cultures were identified as Fusarium proliferatum based on morphological characteristics (Leslie and Summerell 2006). To confirm morphological identification, the RNA polymerase II subunit 2 (RPB2) and translation elongation factor 1-α (EF1-α) gene regions of a representative isolate were sequenced (Liu et al. 1999; Geiser et al. 2004) and deposited in GenBank (Accession Nos. RPB2: OP994350, EF1-α: OP994348). Blastn analysis suggested 100% similarity with F. proliferatum strain CBS 131,574 (RPB2: JX162527, EF1-α: JX118983). Phylogenetic analysis with concatenated sequences further confirmed the identification. To fulfill Koch’s postulates, six branch segments from cv. Siirt were wounded with a cork borer 5 mm and inoculated by a mycelial plug of the same size with from actively growing fungus colony margins. Inoculated branches were wrapped with parafilm and incubated at 25 °C in moist chambers. Controls branches were inoculated with sterile PDA plugs. After 5 weeks of incubation dark-brown necrotic lesions appeared on inoculation point of branch segments, while control plants remained symptomless. The pathogen was re-isolated and confirmed morphologically. To our knowledge, this is the first report of pistachio dieback and canker caused by F. proliferatum in Turkey.