This article highlights elements of Peirce's philosophy used by four well-known psychoanalytic authors, Ricardo Steiner, André Green, Bjorn Salomonsson and Dominique Scarfone, showing how contributions from Peirce's ideas could clarify psychoanalytic matters. The subject of Steiner's paper is how Peirce's semiotic could help to fulfill a conceptual gap mainly in Kleinian tradition in relation to phenomena that occur between what are called "symbolic equations" (representations lived as facts, by psychotic patients) and symbolization. Green's writings question Lacan's conception that the unconscious is structured like a language, suggesting that Peirce's signs, particularly the icons and indices, would be more appropriate to think about the unconscious than the linguistics used by Lacan. One of the Salomonsson's papers gives a good example of how Peirce's philosophic notions can be enlightening in the clinical area, as they are used to answer the criticism that words could not be understood by a baby in a "mother-infant" treatment; the other uses Peirce's conceptions to give interesting suggestions about Bion's beta-elements. The last paper, from Scarfone, broadly address the constitution of significations in psychoanalysis, but we will limit ourselves to consider how Peirce's concepts are used in the model proposed by Scarfone.