Nature has been a source of medicinal agents for thousands of years and impressive number of modern drugs have been isolated from natural sources, mainly based on their use in traditional medicine. Various medicinal plants have been used for years in daily life to treat diseases all over the world. They have been used as a source of medicine. This study was conducted to check antimicrobial activity of three plant species of family Mimosaceae (Acacia nilotica L., Albizia lebbeck L., and Mimosa himalayana). Plant extracts showed activity against all test pathogens (Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa, klebsiella pneumonia, Aspergillus niger and Aspergillus flavus). In this research work it was shown that plants showed remarkable activity against all the test pathogens.