Computer aided assessment (CAA) has been used to provide students with a system for formative self-assessment. Students could access the material at any time and two levels of feedback sought to guide further learning. Comparison of two groups of students (those who used all of the material and those who used none) revealed that those students who used the system performed significantly better in the end of module summative assessment. The difference in performance was not observed between these two groups in a similar assessment on material that was not supported by CAA. This points towards the conclusion that the CAA system has made a positive impact upon the learning experience of the students. [Chem. Educ. Res. Pract., 2005, 6 (4), 198-203]