The authors' purpose in this study was to (1) compare the effects of three teaching methods on registered nurses' and licensed practical nurses' knowledge of medication error risk reduction strategies, and (2) to compare registered nurses' and licensed practical nurses' knowledge of medication error risk reduction strategies using a pretest/posttest design. Registered nurses (n = 129) and licensed practical nurses (n = 21) employed by two hospitals constituted the study sample. Subjects were assigned alternately to three intervention groups: videotape (n = 50); instructional booklet (n = 50); and lecture (n = 50). A 38-item test, including true-false, multiple choice, matching items and dosage calculation problems, was administered to subjects in each group before and after the teaching intervention. On the basis of the results, there was no statistically significant difference in total knowledge scores for the three intervention groups (F = 2.07, P = 0.130). Staff development instructors should consider the advantages of a videotape and instructional booklet over the time-intensive lecture strategy.