This study aimed to assess an ultra-diluted (UD) complex as a replacement for an antimicrobial performance enhancer in diets on the growth performance, intestinal health, and in ammatory response of nursery piglets. The experiment lasted 37 d and involved 126 animals weaned at 21±1.3 d, with an initial body weight of 5.62±1.16 kg. Piglets were assigned to 6 dietary treatments in a randomized block design with 7 replicates and 3 piglets per pen as experimental unit. The treatments were: positive control -basal diet + 120 mg/kg of chlorohydroxyquinoline (PC); negative control -basal diet without additives (NC); and NC containing 4.5; 6.0; 7.5 or 9.0 kg of UD additive/ton diet. Performance data were calculated, and daily diarrhea occurrence was observed. Blood was collected for hematological analyses. In the end of experiment, one animal per pen was slaughtered for organ weighing, pH analysis and collection of intestinal samples for histopathology. Feces were collected during experiment, and cecal contents at slaughter for microbiological and antibiogram analysis. There was no difference between treatments on performance. Throughout the study, UD levels were equal to PC regarding diarrhea occurrence. Higher levels of UD complex led to higher values of total leukocytes. The 4.5 treatment showed a reduction in total and thermotolerant enterobacteria populations in piglet feces, and an increase in lactic acid bacteria, compared to PC. All treatments showed less duodenal pathological alterations compared to NC. The use of the UD additive, especially at 4.5 kg/ton, may be a good alternative for replacing chlorohydroxyquinoline in piglet diets.