Adding organic acid to piglets’ diets is known to be helpful in overcoming post weaning syndrome and chloroacetic acid is known to be the main energy source for the epithelial cells of the large intestine. This study investigated the effect of chloroacetic acid on the vivo swine micro flora and gut wall morphology. Thirty-six weanling pigs were allotted to four treatments i.e., T₁, T₂, T_3, T₄. Each treatment was replicated three times with three pigs per replicate. Treatments 2, 3, and 4 received diets containing 0.3%, 0.6% and 0.9% of the basal diet, respectively while T₁ served as control. On the 42^nd day, one animal per replicate were slaughtered and samples from the gut and mucosa were collected and analyzed. The pH of caecum and rectum were increased while the pH of stomach, duodenum and jejunum were decreased. The gut intestinal micro flora was highest in T₁ followed by T₂, T₃ and in T₄ and varied significantly (P<0.05). Morphological evaluation of the gut mucosa did not show any significant difference among treatment. This study showed that feeding chloroacetic acid as antibiotic replacer at 0.3% influenced the composition and activity of the gut micro flora, reduced the pH and may improved the gut wall morphology after weaning.