Abstract: Cowpea contains phytate-P and other nutrients like amino acids which are poorly digested in broilers. Supplementation of such diets with microbial phytase helps to improve digestibility of these nutrients. In 2 experiments the effect of phytase supplementation on the digestibility of crude protein, amino acids and P of cowpea in broilers were investigated. Experiment One, had 6 diets in which 0, 150 or 300 g kg-1 cowpea replaced maize starch and 0 or 500 units of phytase enzyme (Natuphos), in a 3 x 2 factorial arrangement to determine P digestibility and performance of the birds. Experiment Two, had similar diets as in experiment 1 with the objective to determine digestibility of CP and AAs. TiO2 was added as an indigestible marker in the diets and in each of the experiments a total of 288 1-day-old broiler chicks (Ross strain) were used. Phytase supplementation increased (p<0.05) digestibility of P from 55-67% and improved performance of the birds. Cowpea and its interaction with phytase had no significant effect on P digestibility, CP and AAs, except for arginine, glutamic acid and phenylalanine which were reduced (p<0.05). Phytase increased (p<0.05) digestibility of CP and cystine and reduced CP and AA losses on the basal level at zero intakes of CP and AAs. Results suggest that supplementation of cowpea based diets with microbial phytase improved the precaecal digestibility of P, CP and amino acids in broilers.