The present study addresses the incidence of Parkinson's disease in the processing of semantic information during visual word recognition tasks. In order to do so, the performance of a group of patients with Parkinson's was compared with the performance of subjects without neurological impairment in two experiments. We evaluate the effects of presentation time of a semantic prime (Experiment 1) and an ortho-phonologically mediated semantic prime (Experiment 2), and the impact of the lexical frequency of both the prime and the target words. Participants divided into three groups (a clinical group, an age control group and a group of young adults), completed a reaction time lexical decision task in the go-no-go modality. They had to respond by pressing a computer key if the stimulus presented on the screen was a word. Otherwise, the participants should not press any key. The results, based on response accuracy and reaction times, show a semantic deficit in the clinical group, while this group was, nevertheless, sensitive to the frequency of the words and their presentation time. As a whole, the results are consistent with the existing literature, and contribute to a better understanding of the linguistic deficit present in Parkinson's disease.