Xylazine, at a dose of 1 mg / kg bw, was administered by intravenous (i.v.) route in healthy horses and by intra-articular (i.a.) injection in horses after arthroscopic surgery. At scheduled time points, blood samples were taken to determine the concentrations of drug and consequently the pharmacokinetic parameters. The disposition curves, after i.v. and i.a. administration, were described by bicompartmental and non-compartmental model respectively. The results, following i.a. administration, showed a systemic absorption (bioavailability = 56,69% and Cmax = 0.19±0.09 μg/ml). The appreciation of the xylazine absorption from periferical side can not exclude a central action of the drug after i.a. administration.