We investigated the effect of the administration of rat parathyroid hormone-(1-34) on acute or chronic inflammatory processes in different experimental animal models. Fragment 1-34 of parathyroid hormone had an inhibitory effect in all inflammatory acute tests. The dose-response experiments showed that the maximal anti-inflammatory and anti-exudative effects appeared at the dose of 3.30 and 0.33 micrograms/kg, respectively. The anti-inflammatory effect was observed in the first phase of the inflammatory process. In the carrageenin-induced edema test the anti-inflammatory activity began to decline after 180 min. In contrast, this peptide was inactive in the inflammatory chronic test we used.