Both theoretical linguists and trademark lawyers are deeply interested in the similarity and differences between words, but approach the issue of lexical similarity in different ways. This article highlights the contribution that linguistics can make to the comparison of competing trademarks. Using relevant legislation, legal commentary and case studies of linguistic reports presented to South African law courts, the article investigates the kinds of evidence, methods and resources linguists can use to help the courts clarify the question of how similar two competing trademarks are, and looks at ways of presenting theoretical analyses that are maximally comprehensible and useful to the court.