Background There seems to be an increasing sense of hostility or harshness in comments of rotation evaluations submitted by residents. There seems to be an emergence of microaggressions and even hostile comments recently. Millennials are now the largest generation in the US labor force and the prevalent generation of medical learners. This generation grew up in a digital world where expressing their opinion as online comments was the norm. When comments are anonymous, they are more likely to be uncivil, and the lack accountability contributes to writing simplistic evaluations of complicated issues. Microaggressions are “brief and commonplace verbal, behavioral, and environmental indignities, whether intentional or unintentional, that communicate hostile, derogatory, or negative...slights and insults.” Similar to online comments are online evaluations completed by residents. Methods We conducted a qualitative study of all free-form answers in written, electronic, anonymous resident evaluations of rotations and the program from 2 academic years: 2007-2008 and 2017-2018. Rotation evaluations asked for the (a) strengths of the rotation, (b) in what ways the rotation did not meet one's expectations, and (c) suggestions to improve the rotation. In 2007-2008, there were 2934 comments and in 2017-2018, there were 3717. A constant comparison method was used to identify codes and themes within the comments, including a focus on constructive criticism versus microaggressions. Results The majority of negative comments were constructive criticism directed at characteristics of or, more rarely, specific behavior of personnel on the rotation. There were few microaggressions noted in 2007-2008 with the majority found in 2017-2018. Three types of microaggressions were identified. First, an insult was seen as a personal attack that ascribed a negative attribute to the person as opposed to the person's behavior. Second, the use of sarcasm was seen as a hostile response. Third, the use of powerful words that elevated the intensity of the comment (e.g. rabid, horrible, miscreant) or made generalized or absolute statements, for example, using terms like “everyone”, “everywhere”, and “all”. Conclusions Microaggressions have emerged in anonymous, online resident evaluations. The types of microaggressions may inform future research on the implications and impact of microaggressions in medical education.