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ABSTRACT. Ferreira M.C.N., Miranda R., Abidu-Figueiredo M. & Palhano H.B. [Evaluation of the pregnancy rate in multiparous Nellore cows under artificial insemination and fixed-time artificial insemination]. Avaliação da taxa de prenhez em vacas nelore multíparas submetidas a inseminação artificial e inseminação artificial em tempo fixo. Revista Brasileira de Medicina Veterinária, 34(2):152-156,2012. Área de Anatomia, Departamento de Biologia Animal, Instituto de Biologia, Universidade Federal Rural do Rio de Janeiro, BR 465 km 7, Seropédica, RJ 23890-000, Brasil. Email: firstname.lastname@example.org Between November 2009 and May 2010 158 female Nelore lactating and multiparous were evaluated. The animals were initially stratified by body score (≥ 3.0 on a scale of 1 to 5) and randomly divided into two groups after gynecological screening with group I represented by 60 females inseminated by the conventional system (Trimberger method) with two observations of estrus daily with the help of ruffians and group II represented by 61 females were inseminated at fixed time (TAI) after synchronization hormone. All females were exposed to bulls pure of origin (PO) of the Nelore breed from 24 hours after insemination under maintained until the end of the breeding season (February 2010). The overall pregnancy rate was assessed 60 days after the end of the season through the diagnosis by rectal palpation. The results, expressed as total pregnancy rate showed no significant difference (p> 0.05) compared to groups I and II, 88,3% and 83,6% respectively. According to the results of the use of TAI represented a good tool for reproductive management eliminating the detection of estrus, increasing the number of animals inseminated early in the season which enables.