Entamoeba gingivalis and Trichomonas tenax are protozoa existing in the oral cavity and are typically detected in the periodontal pockets of teeth in humans. This study aimed to determine the prevalence of E. gingivalis and T. tenax infections among people in Zawia city. Another objective was to find any relationship between parasitic infections and some factors of human behaviours. All the participants filled out questionnaires that covered the oral health status, as well as drinks and smoking. The population for this study included 280 participants, the samples were taken from the tooth surface of the fouling materials using sterile swabs. Then they were examined by wet mount smear for the diagnosis of E. gingivalis and T. tenax under the light microscope. The prevalence of E. gingivalis infection was found to be 77.47 %. Specifically, 51.67% of males and 25.8% of females were infected. Very high occurrences of T. tenax among people were detected (74.29 %). Most of the E. gingivalis infections were accompanied by T. tenax (48.39 %). In males, the prevalence of the infection in those with good and bad oral hygiene was 14.3% and 62.5 %, respectively, and of a significant statistical difference. Similar findings were measured in females, where the infection prevalence was equal to 60.7 % and 16.1 % among those with good and bad oral hygiene, respectively. Moreover, a significant relationship between the occurrence of infection and smoking was established. The highest infection rate was found in smokers (78.4%) compared to those non-smokers (21.6 %) in males. In conclusion, oral protozoa E. gingivalis and T. tenax were found to be of high prevalence among people in Zawia city. Furthermore, the parasitic infection has a close relation to oral hygiene habits and smoking.