Purpose: Swallowing impairment, or dysphagia, is a known contributor to reduced quality of life, pneumonia, and mortality in Parkinson's disease (PD). However, the contribution of tongue dysfunction, specifically inadequate pressure generation, to dysphagia in PD remains unclear. Our purpose was to determine whether lingual pressures in PD are (a) reduced, (b) reflect medication state, or are (c) consistent with self-reported diet and swallowing function. Method: Twenty-eight persons with idiopathic PD (PwPD) and 28 age- and sex-matched controls completed lingual pressure tasks with the Iowa Oral Performance Instrument. PwPD were tested during practically defined ON and OFF dopaminergic medication states. Participants were also stratified into three sex- and age-matched cohorts (7 men, 5 women): (a) controls, (b) PwPD without self-reported dysphagia symptoms or diet restrictions, and (c) PwPD with self-reported dysphagia symptoms with or without diet restrictions. Results: PwPD exhibited reduced tongue strength and used elevated proportions of tongue strength during swallowing compared with controls (p < 0.05) without an effect of medication state (p > 0.05). Reduced tongue strength distinguished PwPD with self-reported dysphagia symptoms from PwPD without reported symptoms or diet restrictions (p = 0.045) and controls (p = 0.002). Conclusion: Tongue strength was significantly reduced in PwPD and did not differ by medication state. Tongue strength differentiated between PwPD with and without self-reported swallowing symptoms. Therefore, measures of tongue strength and swallowing pressures may serve as clinical indicators for further dysphagia evaluation and may promote early diagnosis and management of dysphagia in PD.