Purpose: Periodontal diseases have a multifactorial etiology and their risk factors are influenced by modifiable and nonmodifiable factors. The information on periodontal disease and associated risk factors in the Vietnamese population is sparse. Vietnamese dental patients are specific groups with high dental needs and often have greater overall oral health problems. Thus, the purpose of this study was to examine the relationships of periodontal disease to sociodemographic, health-behavioural, and biological characteristics in Vietnamese dental patients. Materials and Methods: A sample of 243 subjects was selected from the National Hospital of Odonto-Stomatology in Hochiminh City. The sociodemographic and health-behavioural characteristics were investigated by a questionnaire. Oral examination including dental and periodontal conditions was conducted. Bacterial load in tongue coating and hemoglobin in saliva were assessed using the BANA test and Perioscreen test. Results: The Perioscreen test showed moderate sensitivity (0.752) and specificity (0.746) to periodontal disease. The binary logistic regression analyses indicated that older subjects (OR = 2.5), or those who did not frequently visit a dentist (OR = 4.1), brushed their teeth only once a day (OR = 2.5), did not use dental floss (OR = 2.9), were past smokers (OR = 3.1), current smokers (OR = 4.1), or had positive BANA test results (OR = 12.0) were more likely to have periodontal disease. Conclusion: The results revealed the periodontal disease was related to age, dental visit behaviour, smoking behaviour, frequency of tooth brushing, use of dental floss, bacterial load in the tongue coating, and hemoglobin in saliva. Keywords: smoking, bacteria, hemoglobin, periodontal disease, Vietnam