While working with psychotic patients in clinical and institutional contexts, we are sometimes confronted with people who appear to be lying. Our hypothesis is that a lot of the false statements addressed to us in these situations are not actual lies. However, in various institutions, several psychotic patients are wrongly labelled as liars, and are thus stigmatized. In this article, we discuss the conditions of possibility of what we call “lies” with conceptual tools taken from psychoanalysis, the philosophy of ordinary language, and speech acts. We conclude by showing the clinical relevance of our approach.