Among the predisposing agents for inflammatory periodontal lesion dental plaque is the most important, but different local and systemic factors may influence the seriousness or progression of periodontitis. Hormonal changes during pregnancy belong to the systemic aggravating factors. The aim of the present study was to assess pregnant women's oral hygiene knowledge and habits, and if these have a relationship with age, residence, educational level and profession/occupation. Questionnaires were used for the data collection. 275 pregnant women, who underwent prenatal care at the Department of Obstetrics and Gynecology in Szeged, volunteered to answer the questions. The results showed that almost all the women brushed their teeth daily, but only about one third of them used special oral hygiene tools, like dental floss. Many of the women claimed to have gingival bleeding when brushing their teeth. More then 70% visited a dentist during pregnancy. There was a significant relationship between educational level and the use of dental floss (p=0.004) and gingival bleeding (p=0.023) Oral hygiene education, dental and periodontal treatment of pregnant women need more emphasis during prenatal care.