Most of the biomarkers that assess exercise-induced gastrointestinal syndrome (EIGS) require venous blood sampling and substantial analysis procedures, time, and costs. (1) Leukocyte cell counts appears more practical as an immediate screening tool of EIGS that required capillary blood sampling and alined with less overall analysis burden. The study aimed to determine the correlations between total and differential leukocyte cell counts with established EIGS biomarkers, systemic inflammatory response profile (SIR-Profile), and gastrointestinal symptoms (GIS) to indicate the potential utility of immune cell counts as a practical surrogate screening marker for EIGS in field base settings. Male endurance runners (n = 11) completed three experimental trials consisting of 2-hour running exercise on an electric treadmill at 70% VO2max in 25.2 ± 1.8 °C ambient temperature and 43 ± 9% relative humidity. Capillary and venous blood samples were collected pre- and immediately post-exercise to determine leukocyte counts (i.e., total, neutrophil, lymphocyte counts, and the neutrophil: lymphocyte ratio (N:L ratio)) and EIGS biomarkers (plasma concentration of cortisol, I-FABP, sCD14, TNF-α, IL-1β, IL-6, IL-8, IL-10, IL-1ra), respectively. GIS were measured pre-exercise and at 15‑minute intervals during exercise using an exercise specific modified VAS. Absolute leukocyte, neutrophil, lymphocyte counts, and N:L ratio showed weak to moderate positive correlations with cortisol (rs = .535, p < .001; rs = .531, p < .001; rs = .312, p = .035; rs = .332, p = .024 respectively), and moderate to strong positive correlations with IL‑10 (rs = .725, p < .001; rs = .785, p < .001; rs = .434, p = .017; rs = .629, p < .001 respectively). Weak to moderate positive associations were also observed between absolute leukocyte, neutrophil, and lymphocyte counts with IL‑6 (rs = .477, p = .008; rs = .495, p = .005; rs = .374, p = .042 respectively). When analysing relative values, exercise-associated changes in total leukocyte counts were moderately positive correlated with sCD14 (r = .407, p = .048) and IL-6 (r = .575, p = .025), and strongly positively correlated with IL-10 (rs = .682, p = .005). Exercise-associated changes in neutrophil counts were strongly positively associated with IL-6 (r = .683, p = .005) and IL-10 (rs = .639, p = .010). A moderate positive correlation was found between exercise-associated changes in lymphocyte count with cortisol (r = .530, p = .009); while, a strong positive correlation was observed between exercise-associated changes in N:L ratio and TNF-α (rs = .600, p = .018). The magnitude of exercise-associated leukocytosis, neutrophilia, and/or lymphocytosis may potentially act as a surrogate marker for exercise-associated stress and inflammatory responses linked the pathophysiology of EIGS. Further research using exertional-heat stress experimental models may provide confirmation.