One of the problems many students encounter when they first come to university is that they do not have some of the basic mathematical knowledge and/or skills which are needed to facilitate the effective learning of their first year courses. This paper describes a scheme of diagnosis and remedial work, consisting of a multiple choice pre-knowledge test and certain books and programmed materials, some of them specially written for the purpose. Certain knowledge gaps and their causes were identified and the effectiveness of the remedial materials and procedures were evaluated. It was concluded that students found the scheme useful and that they profited from it, and that the role played by tutors in discussing the results of the pre-knowledge test was of fundamental importance.