The purpose of this study was to evaluate the acute immune responses to an upper body tri-set resistance training (RT) session in RT trained individuals. Eighteen young trained men (22·0 ± 1·8 years) were randomly assigned to an exercise group (EG; n = 9) or control group (CG; n = 9). The EG completed an acute tri-set RT protocol using two combinations of three exercises for the same muscle group with six to eight repetitions at 75% of one repetition maximum (1RM) for each exercise. Blood samples were collected before (Pre), and 15 min (Post) and 24 h (P24h) after the acute RT protocol to determine basal and acute total leucocytes and leucocyte subsets counting, interleukin-6 (IL-6), tumour necrosis factor-α (TNF-α) and cortisol. There were significant increases in total leucocytes, monocytes and neutrophils at Post as compared with Pre (P<0·05). Additionally, total leucocytes and monocytes were reduced even at P24h when compared to Pre (P<0·05). There were no significant changes in plasma concentrations of TNF-α, IL-6 and cortisol throughout the measured moments. As compared to CG, EG demonstrated very large effect sizes for total leucocytes, neutrophils and monocytes 15 min postprotocol and a reduction (trivial and small effect sizes) P24h. These results suggest that the tri-set RT session did not exacerbate the acute inflammatory response and might be a good option for variations in RT methods for trained individuals.