BACKGROUND: Tongue thrusting, which often occurs during swallowing in patients with anterior open bite, is considered to show different tongue dynamics from healthy individuals, but the details are still unclear. OBJECTIVE: This study aimed to identify the effect of tongue thrusting on tongue pressure production during swallowing in patients with anterior open bite. METHODS: The subjects were 11 patients with an anterior open bite and 8 healthy volunteers with individual normal occlusion. The patients were divided into a tongue-thrusting group (n = 8) and a non-thrusting group (n = 3). Tongue pressures while swallowing jelly (4 mL) were recorded by a sensor sheet system with five measuring points (Chs1-5) attached to the palatal mucosa. The time sequences, maximum magnitude and duration of tongue pressure, and swallowing time of tongue pressure were analysed. RESULTS: Tongue pressure waveforms in the tongue-thrusting group were quite diverse compared with the other two groups. The duration at the posterior-median part in the tongue-thrusting group was significantly shorter, and the maximum magnitudes at the mid-median, posterior-median and the peripheral part were also significantly lower than in the healthy group. These results suggest that the compensatory tongue thrust action by which the tongue closes the front part of the oral cavity may make it difficult to lift the tongue and transfer the bolus. CONCLUSION: Patients with an anterior open bite and tongue thrusting at swallowing showed diversity of tongue pressure waveforms and noticeably weaker tongue pressures from mid-median to posterior-median regions than healthy individuals.