An instrument has been designed and used to quantify the degree of student dissatisfaction with computer-assisted instruction (CAI) experiences. The instrument, entitled PERPI-LPI, was derived from the service test Perceptions Etudiantes de la Relation Professeur-Etudiants (Student Observations on the Teacher-Student Relationship). It measures the observed experiences and the desired experiences of students on 61 dimensions of teacher-student relationships, using a five-point scale. The difference between observed and desired responses provides an indication of student dissatisfaction. The test was administered to 35 secondary students who had taken a CAI course in data processing. Results indicated that student-machine interaction needed to be made more rapid and flexible and that machine failure could be reduced. In addition, it was found that the measuring scales needed improvement and that test modules should be constructed so that it would be possible to adapt situation specific instruments to appropriate contexts. (PB)