The distribution of tylosin was studied using a crossover design, in six pigs following i.v. and i.m. administration of 10 mg kg-1 b.w. Plasma samples were analysed by HPLC and UV absorbance detection. After i.v. administration, t1/2β was 271.3 min, Vd 14.6 L kg-1, Vss 9.7Lkg-1 and CL 26.8 mL min-1 kg-1. After i.m. administration, a Cmax, Of 1 μg mL-1 was reached at 90 min. Mean absorption time was 1988.7 min and bioavailability was 95%. © 2002 Elsevier Science Ltd. All rights reserved.