OBJECTIVE To determine the effect of a 45° reclining sitting posture on swallowing in patients with dysphagia. METHODS Thirty-four patients with dysphagia were evaluated. Videofluoroscopic swallowing study was performed for each patient in 90° upright and in 45° reclining sitting posture. Patients swallowed 5 types of boluses twice: sequentially 2 mL thin liquid, 5 mL thin liquid, thick liquid, yogurt, and cooked rice. Data such as the penetration-aspiration scale (PAS), oral transit time (OTT), pharyngeal delay time (PDT), pharyngeal transit time (PTT), residue in valleculae and pyriform sinuses, premature bolus loss, and nasal penetration were obtained. RESULTS The mean PAS on the 2 mL thin liquid decreased significantly in the 45° reclining sitting posture (p=0.007). The mean PAS on 5 mL thin liquid in the 45° reclining sitting posture showed decreasing tendency. The residue in valleculae decreased significantly for all boluses in the 45° reclining sitting posture (p<0.001, p=0.002, p=0.003, p<0.001, p=0.020, respectively). The residue in pyriform sinuses increased significantly on 5 mL thin liquid, thick liquid, and yogurt (p=0.031, p=0.020, p=0.002, respectively). There were no significant differences in OTT, PDT, PTT, premature bolus loss, and nasal penetration between both postures. CONCLUSIONS PAS on 2 mL thin liquid and residue in valleculae on all types of boluses were decreased in a 45° reclining sitting posture. Therefore, we believe that the 45° reclining sitting posture on swallowing is beneficial for the patients with penetration or aspiration on small amounts of thin liquid and large amounts of residue in valleculae.