Aim: To evaluate the effect of an educational intervention on the bra knowledge and bra wearing behaviour of adolescent females. Method: Adolescent female athletes (n=115; 14-18 years) had their bra fit and design knowledge and bra wearing behaviour assessed by a self-administered survey and Bra Fit Assessment Test (BFAT). The experimental group (n=54) were given an educational booklet related to good bra fit and bra design. The control and experimental groups were retested at 1 and 4 months post-intervention. Results: Bra knowledge between the groups did not differ significantly pre-intervention (p<0.01; experimental=41%; control=40%). However, post-intervention, the experimental group significantly (p<0.01) improved their bra knowledge, with a mean mark of 66% compared to 44% in the control group. Similarly, at pre-intervention, only 12.5% (experimental) and 20% (control) passed the BFAT with only 19% (experimental) and 27% (control) deemed to be adequately supported. Post-intervention, the experimental group showed significant (p<0.01) improvement, with 56% passing the BFAT compared to 15% of the control group, and 51% of experimental subjects deemed to be sufficiently supported compared to 22% of the control group. Conclusion: Adolescent females were found to have poor bra design and fit knowledge and a poor ability to fit themselves in a well-fitting supportive bra, which was appropriate to their physical pursuits and breast size. A simple educational intervention was found to be effective in improving both the bra knowledge and bra wearing behaviour of these females and may encourage the maintenance of physical activity and hence health of this group as they age.