Raw mango (Mangiferera indica L) seed kernels were found to contain tannins (56.5 g kg-' DM), cyanogenic glucosides (64 mg kg-' DM), oxalates (42 mg kg-I DM) and trypsin inhibitory activity (20 TIU g-' DM). The contents of these anti-nutritive factors were lowered by both soaking and boiling treatments, but boiling was more effective. The in oitro protein digestibility (26.3%) and apparent metabolisable energy (7.88 MJ kg-I DM) values of raw kernels were low, and these parameters were improved by soaking and boiling. The observed improvements paralleled reductions in tannin contents, indicating that tannins are largely responsible for the poor nutritive value of raw kernels. In experiment 1, diets containing 0, 50, 100, 150 and 200 g kg-' raw mango seed kernels that replaced maize were fed to 7-day-old White Leghorn cockerels for 14 days. Inclusion of more than 50 g kg-' raw kernels lowered ( P < 0.05) the weight gains, feed intake and feed efficiency of chicks. High level inclusion of raw kernels had toxic effects, as evidenced by increased mortality. In experiment 2, soaking and boiling treatments improved ( P < 0.05) feed intake of chicks fed on diets containing 100 g kg-' kernels and reduced mortality. Feed/gain was unaffected y processing. Soaking had no effect, whereas boiling of kernels improved 100 g kg-' boiled kernels were numerically, though non-significantly, lower than those of the maize-control group. It is concluded that raw mango seed kernels are unsuitable as a feed ingredient in chick diets and, that soaking and boiling do not completely overcome the anti-nutritive effects of raw kernels.