Ribosomes are macromolecular complexes responsible for protein synthesis, comprising ribosomal proteins (RPs) and ribosomal RNA. While most RPs are present as single copies in higher eukaryotes, a handful of them have paralogues that emerged through duplication events. However, it is still unclear why a small subset of RP paralogues were preserved through evolution, and whether they can endow ribosomes with specialized functions. In this review, we focus on RP paralogue pairs present in humans, providing an overview of the most recent findings on RP paralogue functions and their roles in ribosome specialization. This article is part of the discussion meeting issue ‘Ribosome diversity and its impact on protein synthesis, development and disease’.