The literature reports a sex-related asymmetry in the ability to process different semantic categories: women are more proficient with biological categories and men with man-made objects. The origin of this asymmetry is still debated. In this study, we directly checked whether the acquisition of names belonging to different semantic categories differs according to sex. We carried out our inquiry on 202 children aged 3–5 years, who were given a coloured picture naming task using a battery of 60 stimuli belonging to different semantic categories. Boys differed from girls only on naming of stimuli belonging to the categories of tools and vehicles, where they showed an earlier name acquisition. No sex differences were found for animals or plant life, notwithstanding evidence in the literature of an overrepresentation of males among patients affected by biological categories impairment. Our findings suggest that the male advantage for tools and vehicles reported in the literature on verbal fluency and naming tasks is strongly related to the earlier age in males of name acquisition for these categories, and possibly to their higher familiarity. On the contrary, the female advantage for plant life knowledge, which becomes evident later in life, has a still undefined nature and only a dubious relationship to familiarity, although it is sufficient to cause an overrepresentation of males among patients affected by a category specific impairment of biological categories, especially of plant life knowledge.