Abstract: In the current study the claimed antimicrobial activity of Sudanese medical plant, Guiera senegalensis leaves studies. This involved preparation and use of metanolic extract of Guiera senegalensis leaves. The study conducted on Guinea pig and rate with induced inhibition and slight contraction. The extract showed dose dependant inhibition on force and rate f contraction of isolated Guinea pig atrium. In isolated rate uterus preparation the extract showed slight contraction which blocked by (2 mg/mL-1) cyproheptidine.