A survey of medicinal plants used locally in the treatment of various diseases was carried out in Bauchi State-Nigeria. A total of 84 medicinal plants were listed. Preliminary antimicrobial activity of the aqueous extracts of the plants was investigated. The results indicated that out of 84 plants, 75 exhibited antimicrobial activity against one or more of the test organisms at a concentration of 200 mg/ml. The extracts were found to show potentially interesting activity against Proteus mirabilis, Pseudomonas aeruginosa, Staphylococcus aureus and Escherichia coli.