Analysis of the composition of the rodeo lechero argentino. The results listed below arise from the study of data from the Database of the Association of Breeders of Dutch Argentino (A. C. H. A.), corresponding to 552.955 lactations closed in the period 2009-2012 and were developed jointly by SNYDER, M.; ANDERE, C.; RUBIO, N.; LARSEN, M. and CASANOVA, D , technical AACREA, the Faculty of Veterinary Sciences (UNCPBA) and the Association of Breeders of Dutch Argentino (ACHA). Among the main observations that arise from the work we mention the average age at 1st lactation of 31 months, the average of 2.7 lactations per cow, an interval between births average of 432 days, the best lactation corresponds to the 3rd, only 7.8% of the cows exceed 5 lactations and only with good fertility reaches 10 lactations.