OBJECTIVE: The aim of this study was to evaluate pregnant women's knowledge about the safety of medications and supplements used during pregnancy and to determine whether there is a difference in knowledge about medications and adverse effects of medications in relation to age, demographic and socioeconomic factors, habit of reading patients information leaflets and number of chronic diseases in medical history. STUDY DESIGN: The study was cross-sectional. STUDY PARTICIPANTS AND METHODS: The collected data were analyzed based on anonymous questionnaires filled out by pregnant women. One hundred pregnant women participated in the research. The anonymous questionnaire was compiled for the purpose of this study and contained sociodemographic data and information about the current pregnancy. Thereafter, a series of specific questions followed, analyzing the knowledge about medications, supplements and adverse effects of medications. RESULTS: A total of 64 (64 %) participants considered that the use of many medications for chronic diseases during pregnancy is not safe, and 98 (98 %) participants knew that some groups of antibiotics could cause adverse effects. Eighty one women (81 %) knew that the use of sedatives during pregnancy could lead to addiction in the newborn. Also, 98 (98 %) participants knew that using supplements before and during pregnancy was beneficial for both mother and child. Seventy seven subjects (77 %) stated that they always read the instructions for use of the medications carefully and always consulted their gynecologist about the adverse effects. CONCLUSION: There was no significant statistical difference in knowledge about medications, supplements and adverse effects of medications in relation to demographic and socioeconomic factors, presence of a chronic disease in the medical history and habits of reading the instructions for the medication use. Pregnant women need to be additionally educated about the safety of medication use during pregnancy.