Background Advances in radiotherapy techniques have improved clinical outcomes, but have also lead to concerns over subsequent acute and late effects. Dysphagia is one such complication that has garnered much attention. This retrospective study, conducted at a tertiary cancer care centre, aimed to analyse swallowing profiles of patients with cancer of anterior two-thirds of tongue, who had undergone surgery and had received adjuvant radiation using either IMRT or 3D CRT, as a surrogate of dose received by dysphagia aspiration-related structures (DARS). Methods The treatment plans of patients treated using IMRT and 3D CRT, from November 2011 to December 2012, were retrieved from the planning system. The swallowing structures (DARS), namely superior, middle and inferior constrictors, base of tongue, larynx with supraglottis, and length of oesophagus, included in treatment volume with cricopharyngeous muscle, were contoured according to RTOG guidelines. Dose volume histograms were generated for these. Constraint doses were statistically derived. University of Washington Head-and-Neck-related Quality-of-Life questions addressing swallowing was used to evaluate swallowing status of patients. Findings A statistically significant subjective correlation was found to exist between doses of swallowing structures, especially the constrictor muscles, base of tongue, and the larynx. Statistically derived probable mean dose-constraints correlated clinically with swallowing status of patients. IMRT had a statistically significant advantage over 3D CRT, in terms of V30 ( p = 0.051), V50 ( p = 0.002), V60 ( p = 0.002), and D80 ( p = 0.023) for the swallowing structures taken together. The probable limiting dose for dysphagia was 63 Gy for the superior constrictor and base of tongue, and 55 Gy for the larynx. Interpretation Our study predicted possible mean dose constraints for the superior constrictor, base of tongue, and larynx. Further prospective studies are required to confirm these findings. Dysphagia-optimised IMRT is needed to improve swallowing status and quality of life in these patients.