The relevance of a semantic feature measures its contribution to the "core" meaning of a concept. In a naming-to-description task, we investigated the predictive power of relevance in comparison with frequency, familiarity, typicality, and Age-of-Acquisition. In a group of Alzheimer patients with semantic disorder, relevance turned out to be the best predictor of name retrieval accuracy in a naming-to-description task. The same pattern of results was observed in normal controls. Relations between semantic relevance and the parameters of the concepts are discussed in order to highlight the mechanism of concept activation in a naming-to-description task.