In this paper, we examine the use of an ordinary differential equation in modelling the SARS outbreak in Singapore. The model provides an excellent example of using mathematics in a real life situation. The mathematical concepts involved are accessible to students with A level Mathematics backgrounds. Data for the SARS epidemic in Singapore are used for a detailed study. Beginning with a simple logistic model, we discuss how it may be analysed, refined and improved. The exercise serves to provide insight into the processes involved in deterministic modelling using a realistic and relevant example.