This paper describes and evaluates a new method of assessment in PBL, which was developed with two cohorts of dental students. The method involves students in PBL groups designing PBL problems and assessment tasks that are in line with the objectives of the course and the principles of PBL. Construction of tasks and feedback were provided. The student groups based the summative assessment on a selection of the PBL assessments provided. The evaluation indicates that senior students are capable of designing challenging PBL assessment tasks that are in line with course objectives and PBL principles. This experience raised the pass rates of the students compared those of with earlier cohorts of students. The students rated the method favourably; they considered it enabled them to demonstrate their competences and that it was more closely in line with PBL principles than other methods of assessment that they had experienced. The method is a promising innovation, which could be used in a variety of PBL courses.