For decades, educators have advocated using history of mathematics in mathematics classrooms. Empirical research on the efficacy of this practice, however, is scarce. A quasi-experiment was used to investigate the effects of using history as a tool to teach mathematics on grade 11 students' mathematics achievement. Effects in three affective domains (attitudes, anxiety, and motivation) were also measured. Four classes from a school in Singapore participated in this quasi-experiment. The experimental group (n?=?51) and control group (n?=?52) were each made up of two classes. Results indicated that using history as a tool to teach mathematics had a significant positive effect on students' mathematics achievement, in an initial posttest and in two retention tests taken 4 months and 1 year, respectively, after the last intervention session. Significant positive effects were also found on two subscales within the affective domain variables (perceived value of mathematics and introjection, a type of extrinsic motivation), but only at a posttest administered midway through the study. These results suggest that using history in mathematics classrooms have both immediate short- and long-term effects on students' achievement, but only short-term positive effects in the affective domains. These results were discussed using qualitative feedback obtained from the participants of this study.