Aim: To determine antimicrobial activity of Teucrium creticum (T. creticum) leaves extract against bacterial and fungal reference strains and multidrug resistant bacteria isolated at an oncology ward. Study Design: Cross-sectional study. Place and Duration of Study: The study was carried out in department of biology and biotechnology in An-Najah National University in cooperation with the laboratory of the hospital of the university. An-Najah National University is located in West Bank in Palestine. The research was performed from 8th of February to the 15th of April 2017. Methodology: Teucrium creticum plant leaves were collected in Palestine, from which aqueous and methanolic extracts were prepared. Antimicrobial activities of T. creticum extracts were determined against reference bacterial and fungal strains as well as against 8 multidrug resistant bacteria isolated at an oncology ward. Antibacterial and anti-yeast activities were determined by Micro broth dilution method, while anti-mold activities were determined by agar dilution method. Teucrium creticum methanolic extract strongly inhibited the growth of the studied reference bacterial strains, which were Staphylococcus aureus (MIC= 1.56 mg/ml) and Shigella sonnie (MIC=3.125 mg/ml). In addition, most of the 8 multi-drug resistant bacterial strains isolated from patients with cancer (Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia Coli and Enterobacter cloacae) were also highly susceptible to methanolic extract (MIC=3.125 mg/ml). Both the Staphylococcus aureus and Shigella sonnie reference strains were inhibited at lower level by the aqueous extract (MIC=12.5 mg/ml). All the bacterial strains isolated from patients with cancer were susceptible to aqueous extract at different levels (3.125 – 25 mg/ml). Epidermophyton floccosum mold and Candida albicans yeast were strongly inhibited by aqueous extract, where the MIC values were 1.56 and 3.125 mg/ml, respectively. Conclusion: T. creticum plant extracts showed promising antimicrobial activities against multidrug resistant bacterial isolates as well as against reference bacterial and fungal strains.