This article was migrated. The article was marked as recommended. Background The Association of Faculties of Medicine of Canada, Future of Medical Education in Canada report shared a collective vision to improve social accountability, including a review of admissions policies to enhance student diversity. This study explored if and how the Medical College Admissions Test (MCAT) might mediate the socioeconomic diversity of Canadian medical schools by quantifying the costs and other cost-related factors of preparing for the exam. Methods A 34-question anonymous and bilingual (English and French) online questionnaire was sent to the 2015 first-year cohort of Canadian medical students. Developed collaboratively, the survey content focused on MCAT preparation and completion activities, associated costs, and students' perceptions of MCAT costs. Findings The survey response rate was 32%. First-year medical students were more likely than the Canadian population to belong to high-income families (63% vs. 36%) and less likely to be from rural locations (4.5% vs. 19%). Use of MCAT preparation materials was reported by nearly every MCAT test-taker (95.3%): of those, 76.4% used free practice tests; 59.8% paid for practice tests; 45.1% registered for preparation courses; and 3.3% hired a private tutor. In terms of writing the MCAT, the total economic costs per respondent are estimated at $6,357 ($4,755-$7,958) and total direct costs per respondent are estimated at $2,970 ($1,882- $4,058). Opportunity costs represented the majority of economic costs, at $3,387 ($2,872 - $3,901), or 53.2%. MCAT preparation costs are estimated to be $2,372 ($1,373-$3,372), or 79.9% of total direct costs and 37.3% of economic costs. Most respondents agreed, 76%, that the MCAT posed a financial hardship. Conclusion The financial demands of preparing for and completing the MCAT quantified in this study highlight an admissions requirement that is likely contributing to the current student diversity challenges in Canadian medical schools. In the spirit of social accountability, perhaps it is time to prioritize equitable alternative for assessing applicants' academic readiness for medical school.