In recent years, grapevine trunk diseases are frequently encountered in the vineyards of the world, including Turkey. The aims of this study were to identify grapevine fungal trunk pathogens in vineyards in Gaziantep Province, Turkey, and to investigate antagonistic relationships of fungal endophytes with the fungal trunk pathogens. The survey study was conducted in 51 vineyards located in Şahinbey, Nurdağı and Islahiye districts in September 2020 and the disease prevalence and incidence were determined. Antagonistic associations between endophytic and pathogenic species were investigated with a dual culture test in PDA (potato dextrose agar) medium. Local drying, dieback and apoplexy symptoms were observed in all the vineyards inspected and the mean disease frequency in individual vines in the study area was calculated as 1.2%. Identification studies and pathogenicity tests indicated that the vineyards were infected with species of the genera, Biscogniauxia, Botryosphaeria, Cytospora, Diatrype, Diplodia, Eutypa, Kalmusia, Neoscytalidium, Phaeoacremonium, and Seimatosporium, which are known to be associated with grapevine trunk diseases. Penicillium fructuariae-cellae was found to be antagonistic, with an average 9.04 mm diameter inhibition zone, to most of the grapevine trunk pathogens in the dual culture tests. These results suggest that more attention should be paid to endophytic Penicillia species as novel fungal biological control agents for the management of grapevine trunk diseases.