The present research was carried out to determine whether Jakobson's claim that Broca's aphasic patients emit chiefly semantic paraphasias of the similarity type, whereas Wernicke's aphasic patients produce mainly paraphasic substitutions of the contiguity type, can be supported by data gathered for clinical purposes under controlled conditions. Semantic paraphasias produced by 96 aphasic patients on a standard test of visual naming were taken into account. Three independent judges, blind to aphasia type, classified all responses retained as semantic substitutions into one of the following four categories: those having 1) a strong similarity, 2) a strong contiguity, 3) a mild similarity, and 4) a mild contiguity relation to the correct word. No relationship was found between type of semantic paraphasias and clinical form of aphasia. Furthermore, irrespective of the clinical form of aphasia, aphasics tend to give more similarity substitutions than contiguity substitutions.