The traditional medicine still plays an important role in the primary health care in Brazil. In this report, 23 plants were selected and collected in different physiognomy from Parque Nacional do Catimbau, Northeastern Brazil. The dried plants were separated into leaves, fruit, stem-bark and roots. Each part was extracted with aqueous, ethanolic and hydroalcoholic extracts, and 54 crude extracts were prepared. The extracts were tested for their antimicrobial activity using three Gram-positive bacterial strains (Bacillus subtilis, Micrococcus luteus and Staphylococcus aureus), two Gram-negative bacterial strains (Escherichia coli and Klebsiella pneumoniae) and Candida albicans. In addition, a phytochemical screening of ethanolic extracts of five species was done. The highest antimicrobial activity was exhibited by the hydroalcoholic extracts of leaves of Buchenavia tetraphylla and ethanolic extracts of fruits of Libidibia ferrea var. ferrea against Mycrococcus luteus. The phytochemical screening demonstrated the presence of different types of compounds like flavonoids, terpenoids and others, which could be responsible for the obtained activities. The presence of antibacterial activity could be confirmed in species used in traditional medicine in Caatinga which were assayed in this study. This is the first report about antimicrobial activities of some plants namely Chamaecrista desvauxii, Melocactus zehntneri and Stigmaphyllon paralias.