SUMMARY -Th e purpose of the research was to compare oral health behavior and plaque indices between Croatian fi rst-year and fi nal-year dental students. Th erefore, 46.9% of fi rst-year and 47% of fi nal-year dental students were surveyed using the Hiroshima University Dental Behavior Inventory (HU-DBI) questionnaire and had their plaque indices determined. Descriptive statistics analysis, nonparametric tests, and correlation analysis were performed (p<0.05). Sixth-year students had a signifi cantly better mean HU-DBI score (8.06) than fi rst-year students (6.45). Signifi cantly more fi rstyear students thought that they could not help having false teeth at their old age (p=0.007), had never been taught professionally how to brush (p=0.019), and used a toothbrush with hard bristles (p=0.001). Signifi cantly more fi nal-year students brushed each of their teeth carefully (p=0.008), thought they could clean their teeth well without using tooth paste (p=0.000), used a dye to see how clean their teeth were (p=0.002), and had their dentist telling them they brushed very well (p=0.028). Plaque index values were signifi cantly lower (p<0.05) among fi rst-year (7.94±0.72) than among fi nal-year (9.13±0.77) students. With advancement in dental training, oral health attitudes improved, but the level of dental students' oral hygiene decreased.