The aim of this study was to determine the prevalence of usage and the knowledge and attitudes towards dietary supplements among medical sciences and nonmedical sciences students from Croatia. The study was conducted based on a questionnaire about dietary supplement usage, knowledge and attitudes. The prevalence of dietary supplement use, among 910 university students was 30.5%. The most-used dietary supplements were vitamins (18.0% in medical sciences students and 9.8% in non-medical sciences students). For all students, the internet (66.1%) was the most common source of information, followed by healthcare professionals (33.2%). The most common reason for taking dietary supplements was to maintain good health (26.4%). Use of the internet rather than health professionals as a trusted information source should be revised among this young population. Supplement intake was significantly associated with body mass index (BMI) (p = 0.016) and physical activity (p = 0.050). Students with normal BMI (61.5%) and the most physically active students (37.7%) took significantly more dietary supplements. Results of this study could help medicine faculties to improve their curriculum and support the development of public health messages aimed at wise and safe use of dietary supplements.