The microscopes and slide sets used in the first-year histology course at the Medical College of Pennsylvania were supplemented by a videodisc-based histology atlas. We evaluated the impact of this technology on teaching in the laboratory setting and on the performance of 133 students on a laboratory exam. Interviews and questionnaire responses from students and faculty indicated that the videodisc system was well liked, easy to use, and often preferred to the microscope as a learning tool. The videodisc system provided a locus for student-student and student-staff educational interactions. An increase from the previous year in student lab practical scores was only partially accounted for by differences in the class composition. While some of the score increase may be due to a change in format of the exams, observation and interviews with students and teachers suggest that some of the score increase was attributable to the greater learning efficiency made possible by the videodisc atlas.