Thirteen teachers lecturing to first and second year students at the University of Rochester, School of Medicine and Dentistry were studied. The investigation was designed to identify aspects of teaching, through the use of:(1) questionnaires to students; (2) questionnaires to the teachers; and (3) by means of a classroom interaction analysis instrument, the Sequential Analysis of Verbal Interaction (SAVI). The findings showed that few among possible categories of expression were used in lectures. The categories most frequently recorded were Description, Opinion, and Proposal. Two teachers were identified as expressing more Opinion than the others, and two other teachers were similarly identified as having a more descriptive style than the others. Both teachers who were found to use Opinion often were for the most part regarded by the students as being less effective. One teacher who was found to use Description most often was one of the best regarded teachers.