The purpose of the present research is to compare the effects of a Direct Instruction flashcard procedure on the mastery of multiplication facts by two high school students with attention deficit hyper-activity disorder (ADHD) and oppositional defiant disorder (ODD). Both students were enrolled in a separate high school for students with behavior disabilities. The effectiveness of the Direct Instruction flashcard procedure was evaluated across three different sets of math problems using a multiple baseline design. In addition, the effectiveness of various ratios of mastered to unmastered facts was examined. The overall outcomes indicate a large increase in correct responding by both of the participants during the Direct Instruction Flashcard System. An intermediate ratio of mastered to unmastered facts was correlated with fewer trials to mastery for each participant. The applicability of employing Direct Instruction flash card procedures was discussed and directions for future research were posed. (Contains 2 figures.)