Background: Antibiotic resistance is one of the most serious biomedical problems that require new agents to combat bacterial pathogens. Potassium aluminium sulphate (alum) has recently drawn the attention of the scientific community as an efficient, safe and eco-friendly inorganic compound with antimicrobial activity. Methods: Ten samples of bacteria, five types of Eschericha coli (E. coli) and five types of S. aureus were isolated from patients. Eschericha coli isolated from urine sample by sterile container. Staphylococcus aureus (S. aureus) isolated from wound samples by a cotton swab. The samples were cultured on the following media (Mannitol salt agar, eosin methylene blue agar, and blood agar). Well diffusion method used to evaluate the antimicrobial activity. Alum aqueous solution with two concentrations (1% and 2%) was determined as well as amoxicillin, gentamicin, and ceftriaxone. Results:  E. coli is sensitive by 50%for both concentrations of alum (1%, 2%), S. aureus is 100% resistant to a concentration of 1% of alum and 50% resistant to a concentration of 2% of alum. Combination of amoxicillin with alum for each concentration (1% and 2%) has no significant effect on the activity of amoxicillin for both E. coli and S. aureus (p= 97 and p= 0.62) respectively. Combination of ceftriaxone with alum for each concentration (1% and 2%) has no significant effect. The combination of gentamicin with alum for each concentration in E. coli has no significant effect. But for S. aureus the mean of gentamicin sensitivity was 39.50± 3.87, the mean is decreased after combination with 1% alum 41.50± 4.35 and 2% alum 40± 5.83 with significant statically differences (p= 0.02). Conclusions: The white alum effect is dose response, and greater concentration will lead to enhanced decrease on bacterial growth. This study suggests more than 1% and 2% concentrations of white alum could be used as antimicrobial agent. The effect of 1% and 2% alum combined with ceftriaxone and amoxicillin shoed no significant differences (p> 0.05).