Objective: The aim of the study was to examine the knowledge and habits of maintaining oral hygiene of high school and university students in the city of Osijek and to compare the results collected by the study. Study Plan: Cross-examination research was carried out in the city of Osijek. Participants and Methodology: The survey included 190 participants from the area of the city of Osijek and was conducted in the period from February to June 2022. 86 participants were high school students of the Electrical Engineering and Traffic School Osijek, the other participants were students at the University of Osijek. An individual survey was created for the research. The survey questionnaire consists of a total of 15 questions with multiple answers offered. Results: There were 190 participants who took part in the study, of which 92 (48.4 %) were female and 98 (51.6 %) were male. Females brush their teeth more often on a daily basis, compared to males (Fisher's exact test, P = 0.02). Among the participants who brush their teeth once a day, there were significantly more males, and more often they stated that they do it only in the morning or only in the evening before bedtime, than females did. University students brushed their teeth more often than high school students (Fisher's exact test, P = 0.003). High school students spent more time brushing their teeth (Fisher's exact test, P = 0.02). Conclusion: The results indicate that males have worse habits of maintaining oral hygiene than females in the city of Osijek. Also, university students have a higher frequency of brushing their teeth than high school students.