Abstract: To investigate the effect of raw and heat treated cowpea on the GIT and growth performance of pigs, 48 weanling piglets were divided into 4 groups and fed diets containing either 30% soymeal (T1) as controls, or 30% heat-treated cowpea (T2), or 15% heat-treated and 15% raw cowpea (T3), or 30% raw cowpea (T4). Phase 1 of the feeding trial started immediately after weaning and lasted for 18 weeks. From the 19th week, T4 group was subdivided into 4 groups and they were fed either T1, T2, T3 or T4 for 16 week. Average Daily Gain (ADG) was lowest in T4 group both in phase 1 and phase 2 (p< 0.01). Marked hypertrophy of the villi and crypt hyperplasia were seen in the jejunum and duodenum (p< 0.01) of T4 group. The diminished growth and marked enteropathology in the T4 group was attributed to the heat sensitive ANFs in the raw cowpea. However, in phase 2 of the trial, when substitution feeding was implemented in the T4 group, they showed marked improvement in feed consumption and weight gain. The catch-up growth seen after the introduction of substitution feeding, indicates that the antinutritional effects induced by the raw cowpeas are reversible. Heat treated cowpeas could make a valuable contribution in substituting soyabeans in animal feed.