Introduction: There is abundant evidence that rural origin is an influence on rural career choice. Rural origin is widely used to select students to be supported into programs designed to address the rural medical workforce shortage. What is not as clear is how many years of rural upbringing are required to have a maximal effect on rural career choice. Neither is the place of having a sense of rural background well understood., Methods: A cross-sectional self-completed paper-based survey of all students in years one through four of the Monash University medical course was undertaken in 2003. The survey included a scale to measure stated rural career intention as well as questions about the number of years of rural upbringing and whether students had a sense of rural background. The Rural Intention score was divided into three categories: strong urban intent, strong rural intent, and an intermediate, less certain intent., Results: There was an 88% (n = 399) response rate from students holding Commonwealth Supported Places. Approximately 30% of these claimed a sense of rural background, and 28% had more than 8 years of rural upbringing. Twenty-five percent stated a strong intention to choose a rural career and 34.5% had strong urban intent. The remaining 40.5% were in the intermediate group. Almost all students (97.5%) with over 5 years of rural upbringing had developed a sense of rural background, and almost all (97.5%) with less than 5 years' rural upbringing denied a sense of rural background. Rural intent was high for those with a sense of rural background and those with more than 8 years of rural upbringing, but the students who had had from 4 to 8 years of rural upbringing mainly fell into the 'uncertain' category., Discussion: In this cohort of almost 400 Australian medical students, a sense of rural background developed at a clear point, around 5 years of rural upbringing. Students with a sense of rural background were likely to develop a strong rural intent several years before similar students who had failed to make this connection with a rural community. This latter group displayed uncertainty toward a rural career choice, possibly due to unfamiliarity. Unlike those with strong urban intent, these students have not excluded a rural career and should be supported. The inclusion of a measure of the intention of students to work in a rural environment is likely to increase the reliability and validity of selection procedures.