Minor illnesses in children are often cured at home with over the counter medicines. Even though there is a wide use of medicines among children, they rarely receive medical advice about their medications from doctors or pharmacists. The aim of this study is to evaluate children's beliefs about medicines as well as to explain what children know about medicines. A cross-sectional survey was used to collect data from four primary schools in Penang Island, Malaysia. The target population of this research was schoolchildren of 11 and 12 years old regardless of their gender and social status. A self-administration questionnaire was used to obtain the data from schoolchildren and their parents. After including all schoolchildren in grades five and six, the total sample size was 1000 children in addition to 1000 parents. This study found that most children have inadequate knowledge and false beliefs about the efficacy of medicines. Children's beliefs about the efficacy of medicines were affected by their age group, gender and race (p < .05). Females, older children and Chinese were more knowledgeable about the efficacy of medicines. Furthermore, the socio-economic status, parents' education level and parents' occupation influenced children's beliefs about medicines (p < .001). This study showed that children have misconception about medicines. The need for medicine education should be implemented to get more knowledgeable users of medicines in future. However, the role of health-care professional should be increased in terms of medicine education.