This study was conducted to determine the antibacterial effect of cinnamon essential oil (CEO) and its nanoemulsion (CNE) on Staphylococcus aureus isolated from luncheon samples sold in Sohag city. Forty luncheon samples were randomly collected from different supermarkets in Sohag city. The samples were examined bacteriology for detection of Staph. aureus. The results revealed that the incidence of Staph. aureus in luncheon samples was 10% (4/40). The minimum inhibitory concentration (MIC) of the prepared CEO and its nanoemulsion CNE were detected in-vitro against the isolated Staph. aureus strains by using agar well diffusion method, in which, the results revealed that the MIC were 0.39% for CEO and 0.78% for CNE. The different concentrations of CEO and CNE have a great effect against Staph. aureus growth and the most effective one at the MIC (0.39%) was CEO with 11.67±0.66 mm.