This study aims to evaluate the allelopathic potential of aqueous extract of leaves and branches of mint under the initial development of seedlings of cowpea (cv. BRS Guariba). This study was developed at the Federal Rural University of Pernambuco, Campus Serra Talhada-PE. Six concentrations were evaluated: 0, 20, 40, 60, 80 and 100% of aqueous extract of leaves and branches of mint. The variables analyzed were seedling emergence, shoot and root length, shoot and root dry matter and stem diameter. The aqueous extracts of leaves and branches of mint in the different studied concentrations had no significant effects on the studied variables, except for root length of seedlings submitted to mint leaf extract. However, when compared with the extracts from branches and leaves, it is observed that the leaf extract caused a decrease in all variables in relation to those of branches. Possibly, this result indicates that the extract from leaves of mint contains a secondary metabolic at a higher concentration, delaying the initial development of seedlings of cowpea.