Various gelatinizers, which facilitate oral ingestion, are employed in patients with dysphagia. The purpose of this study was to histologically clarify the influence of various gelatinizers on the lung, using rats. We administered 0.2 ml/kg of 0.1% xanthangam, a 0.25% commercially available xanthangam gelatinizer, 0.35% ι-carrageenan, 0.5% κ-carrageenan, 1% gelatin, 0.15% agar, physiological saline, tap water, and isopropanolpurified 0.1% xanthangam/0.35% ι-carrageenan into the trachea of 8- to 9-week-old male SD rats. The lungs were extirpated after 24 and 72 hours. Neutrophil infiltration in the alveolar space was expressed as the mean number of neutrophils in 30 randomly selected high-power fields. In the xanthangam (451.0 ± 204.0 cells) -, and the ι -carrageenan (424.4 ± 257.2) treated groups, the neutrophil counts after 24 hours was significantly greater than in the physiological saline (33.0 ± 22.6) - treated group (p < 0.05). In the available xanthangam gelatinizer (290.0 ± 86.8) -treated group was no significant difference in the physiological saline-treated group. In the isopropanol-purified xanthangam (90.2 ± 42.3)-treated group, the neutrophil counts after 24 hours were significantly smaller than in the nonpurified xanthangam -treated group.These results suggest that lung tissue inflammatory response-inducing features depend on the type of gelatinizer. On the other hand, purification reduces the lung-damaging features of xanthangam.