This research aims to explore the concept of mental model of students about genetic concepts through drawing-writing test. The participants were 85 students of Biology Education at University of Lampung, which has taken genetics course. Mental model of students was categorized into five levels (levels 1-5) based on coding framework which was adapted from Kose (2008) and Saka et al. (2006). The results showed that the most dominant mental models found in each concept through drawing-writing test (D/W) respectively were D3/W3 (drawings with misconceptions/partial understanding with alternative conceptions) on the concept of "genetic materials", D2/W2 (non-representational drawings/alternative conceptions) on the concept of "heredity", D2/W3 (non-representational drawings/partial understanding with alternative conceptions) on the concept of "gene expression", D2/W3 (non-representational drawings/partial understanding with alternative conceptions) on the concept of "gene regulation in metabolic processes", and D1/W2 (no understanding/alternative conception) on the concept of "gene regulation of the growth and development of an organisms". The results indicated that drawing-writing test can be used in probing the learning difficulties and misconseption on genetics.