The perceptions of students who study environmental science related to pollution are certainly different because they are influenced by various circumstances. These circumstances, among others, depend on what they observe around them and their prior knowledge. This study aimed to determine the concept of pollution according to the cognitive structure of prospective biology teachers. The research was designed as a case study and the selected participants were 29 first-year biology education students who took environmental science courses. Data were collected by giving word association tests, open-ended questions, and drawings. The results showed that students' thinking process and prior knowledge influenced their ability to express ideas or answers. Cognitive perceptions of prospective biology teachers from the word association test brought up 30 words related to the pollution which were grouped into four categories, namely types of pollution, causes of pollution, consequences of pollution, and solutions to overcome pollution. Cognitive perceptions of prospective teachers based on open-ended questions, most of them wrote the definition of pollution as stated in the environmental management law, and cognitive perceptions of prospective teachers outlined in the form of drawing related to efforts to overcome pollution are throwing garbage in its place, doing reforestation, and go green action. [Note: The publication year (2023) shown in the citation on the PDF is incorrect. The correct publication year is 2024.]