The type 1 abomasal ulcer (AU1) does not have specific clinical signs, so there is a need to identify some early biochemical markers for its diagnosis in cattle and buffaloes. The plasma gastrin is reported to reflect the gastric mucosa damage but its utility for the diagnosis of AU1 in buffaloes has not been evaluated. The objective of this study was to investigate the test performance of plasma gastrin to distinguish between healthy buffaloes and the buffaloes with AU1. Twenty-three buffaloes with AU1 and six buffaloes without any abomasal ulcer were used. The blood samples were collected from buffaloes, slaughtered in a buffalo specific slaughterhouse for estimation of the plasma gastrin. After slaughter the abomasa were examined for the presence of AU1 and the blood samples were collected for estimation of plasma gastrin. The mean plasma gastrin concentration of the ulcer-positive buffaloes was significantly (P<0.05) higher than the ulcer-negative buffaloes. The receiver operating characteristic curve analysis suggested that the optimal value of plasma gastrin for the diagnosis of AU1 was 106.2 pg/mL. This preliminary work suggests that plasma gastrin could be a valid diagnostic test for the detection of AU1 in the buffaloes. The sensitivity, specificity, positive predictive value and negative predictive value of the plasma gastrin to diagnose AU1 in the buffaloes were 78.3, 100, 100 and 69.9 pg/mL, respectively.