Delusions are one of the most elusive concepts in psychiatry. There have been several theories on the nature and definition of delusions. Jaspers described them as entailing a total transformation of reality and considered primary delusions as un‐understandable. When it comes to clinical practice, psychiatrists resort to criteria of falsity, incorrigibility, conviction and being out of keeping with the person's culture. All these criteria have been subject to various criticisms, some of which will be discussed in the paper. We will use the concept of epistemic injustice to explore the role of stereotypes and prejudice in the identification of delusions. We will discuss cases where patients are suffering from testimonial injustice by virtue of having a mental disorder that is so often associated with attributions of irrationality, bizarreness and incomprehensibility. Two vignettes will be presented to show that this is often the case in clinical practice. We will discuss relevant issues around the epistemology of the delusions. We think that in order to challenge the testimonial injustice, there needs to be an awareness of its possibility and thus recognition of the role of certain stereotypes in assessing these mental states. Challenging the stigma against mentally ill and adopting a holistic view of delusions can help tackle the prejudice that pre‐empt the testimonial injustice.