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The loss of an estrous cycle is critical in any production system. Especially in artificial insemination programs in which the detection of estrus depends on the human factor. The detection of estrus, has been one of the limitations for the massive use of artificial insemination. Therefore, the application of estrus and ovulation synchronization methods is very important in reproductive management in cattle. The objective was to evaluate by ultrasonography two estrus synchronization protocols in beef cows (Aberdeen angus). The research was carried out at the Research and Production Center (CIP) Chuquibambilla of the National University of the Altiplano. The experiment was performed with 30 cows that were divided into two groups of 15 for the first protocol (T1-Ovsynch) and 15 animals for the second protocol (T2-CIDR-synch). The ovarian function for T1 was 50% for both the right and left ovary, while for T2 it was 75 and 25% for right and left ovary, respectively; Presence of corpus luteum (CL) was 75% of cows for T1 and 60% of cows for T2, the follicle growth rate was for T1 of 0.5 ± 0.87 mm and for T2 of 1.2 ± 0.74 mm; The maximum diameter of the ovarian follicle for TI was 8.09 ± 3.23 mm and for T2 of 10.2 ± 3.16 mm and the pregnancy rate for T1 was 33.3% and for T2 of 66.7%. In conclusion, ultrasonographic evaluation is a useful tool for evaluating estrus synchronization protocols. Real-time observation of the synchrony of the emergence of a new follicular wave (at the beginning of the treatments) and ovulation in both protocols, resulting in a higher pregnancy rate.