An underlying yet significant theme in the novel is the oppression of minorities in America by the dominant white power structure. Kesey conveys his concern about the mistreatment of Native Americans through Chief Bromden's recollections of the government taking his tribe's land to construct a hydroelectric dam. He also draws attention to the issue of alcoholism among Native Americans as a result of cultural marginalization.

Additionally, Kesey is attuned to the challenges faced by black individuals. While his depictions of the black orderlies who abuse and degrade the patients are morally disturbing, Kesey illustrates that the absence of job opportunities beyond menial tasks like cleaning floors has led these men to become abusive. Moreover, the backstory of one black attendant, who as a child saw white people assault his mother and torture his father, sheds light on the deep-seated animosity blacks have towards whites. Kesey's message underscores that cruelty fuels racism.