In a study of the development of professional attitudes in medical students, a modified version of the Medical Attitudes Inventory (Harris, 1974) was administered to 141 male and female first year medical students in Lagos, Nigeria. The results show that the students have well-defined attitudes on certain issues and are divided on others. The findings are discussed in terms of their implications for medical education, attitude research and durability of students' attitudes in and beyond medical school. The influence of contemporary social factors on student professional attitudes is also considered. The instrument has sufficient psychometric attributes to warrant further use.