Starting from the idea that there are some basic relative words (pronouns, adjectives, adverbs) in English, this paper aims at highlighting the complexity of these words, viewed from different perspectives. A study upon the English relative words and the English relative clauses would be a real challenge, but it could also prove that these two aspects are special and they are worth studying in order to see whether there are always connections between them or not. The structures and the clauses with relative words offer a good and rich material to work with and to study, enabling us to draw clear, logical and useful conclusions.