Introduction Allen (2017) describes a grade enquiry continuum (GEC) that seeks to characterize student's behaviours with instructors into four categories: grade neutral, grade enquiry, grade challenge, and grade-grubbing. While the process of discussing grades may promote learning, the de-emphasis of content mastery associated with the latter two categories may have detrimental effects. Concerningly, anecdotal reports suggest a high prevalence of grade challenging/grubbing attempts in higher education, and it remains unknown what motivates these adverse behaviours. Thus, this study aims to explore the prevalence of GEC behaviours in undergraduate medical science students, their perceptions about negotiating grades, and the factors that motivate grade challenging/grubbing attempts. Methods In our first objective, a survey was administered to 2,500 undergraduate medical sciences students (n=367 completed) at our institution to examine students’ self-reported prevalence, perceptions and motivations for grade challenging/grubbing. To determine the validity of these reports, we also conducted an observational study with 31 students (n=4 completed) to explore if their self-reported behaviours aligned with their observed behaviours. In our second objective, we explored whether the perception of losing versus earning grades influenced their propensity to grade challenge/grub through an experimental manipulation of how grades are presented on their learning management system (n=31). Focus groups were used in a follow-up with participants to examine the reason for changed/unchanged behaviour or mindset. Results Our survey results indicated that 50% of students who had met with an instructor/teaching assistant before had also negotiated a grade (n=99). Furthermore, of the 40 students in their 4th year answering this question, 65% had negotiated a grade. In addition, results from our second study showed that ≥14 accounts of grade challenging and four accounts of grade grubbing were self-reported over just the course of one semester (n=31). Qualitative findings suggest that many students within the study population are extrinsically driven by career goals and view their grades as a way to competitively distinguish themselves for post-graduate programs. These motivational factors and perceptions towards grades may be influencing these adverse behaviours. Conclusions: This study was the first to quantify self-reported grade negotiation behaviours at a program level. It was also the first to use an experimental design to document and observe these behaviours in a real classroom setting. Our findings clearly show that GEC behaviours are as prevalent as anecdotally suggested. This understanding is necessary moving forward to further investigate whether these behaviours are getting worse, what causes students to exhibit these behaviours and what interventions or actions can be implemented to deter these behaviours in the future.