The present invention relates to selected (R)-arylalkylamino derivatives of formula (I), in which R, R1 and Ar are as defined in the claims. These compounds show a surprising potent inhibitory effect on C5a induced human PMN chemotaxis. The compounds of the invention absolutely lack of CXCL8 inhibitory activity. Said compounds are useful in the treatment of pathologies depending on the chemotactic activation of neutrophils and monocytes induced by the fraction C5a of the complement. In particular, the compounds of the invention are useful in the treatment of sepsis, psoriasis, rheumatoid arthritis, ulcerative colitis, acute respiratory distress syndrome, idiopathic fibrosis, glomerulonephritis and in the prevention and treatment of injury caused by ischemia and reperfusion.