<p><span lang="EN-GB">The aims of this study were to describe level of conceptual understanding and conceptual difficulties on the nervous system from the perspective of pre-service biology teachers. This research was used cross-sectional research design with a sample of 30 participants was selected randomly. The six essays that were created using the conceptual understanding indicator, and twelve multiple-choice questions that were created in the form of three-tier examinations, and the open questionnaires developed to detect challenging concepts in the nervous system make up the instrument. Data has been analysed using descriptive statistics. Data analysis indicates that the average score of conceptual understanding of pre-service biology teachers is 67.33 belongs to the medium category. For the highest percentage of conceptual understanding indicator is ability to exemplify concepts (86.67%) and the other hand, lower percentage is indicators of ability to connect various concepts (46.67%). The best concept for conceptual understanding especially about sub-matter of structure and function of neurons, central and autonomy nerves. Conversely, for the nervous system concepts that are recognized as challenging, particularly the concepts of physiology, impulse transmission mechanism, and somatic nerve inertia. The lack of conceptual understanding caused by complexity of subject, abundance of terminology, and intangible things. The study is expected to be used mainly for development of various learning methods or media that viewed as suitable for improving conceptual understanding of and reducing conceptual difficulties.</span></p>