A study was undertaken to examine the effects of citric acid (CA) supplementation on performance, nutrient retention, intestinal enzyme activities and tissue biogenic amine (BA) content in broiler chickens. Two hundred male chicks were randomly allotted to 5 dietary treatments: a nutritionally balanced basal diet supplemented with 0, 15, 30, 45 and 60 CA g kg–1 of feed from 7 to 42 d of age. The results indicated that final body weight (linear, P< 0.05), average daily gain and average daily feed intake (linear and quadratic, P< 0.05) were significantly improved by the diets containing 30 g kg–1of CA but were suppressed as CA increased to 60 g kg–1.Feed efficiency was improved in the birds fed on diets containing 15 g kg–1of CA (linear, P< 0.05). The specific activities of intestinal hydrolases such as maltase, sucrase and leucine amino-peptidase were not affected by the dietary groups. Citric acid supplementation did not have a significant effect on the retention of DM and crude fat, although CP and P retention, and apparent metabolizable energy corrected to zero nitrogen retention (AMEn) increased linearly and quadratically on increasing CA addition reaching a maximum at 30 g kg–1 diet. Dietary acidification reduced linearly and tended to reduce quadratically total BA (TBA) content of raw chicken breast and thigh. In conclusion, these findings demonstrate that the CA supplementation at 30 g kg–1 of the diet resulted in optimal growth performance and nutrient retention, whereas inclusion of 60 g kg–1 of CA reduced the BA content in raw breast and thigh meat. © Verlag Eugen Ulmer, Stuttgart.