ABSTRAK. Penelitian ini bertujuan untuk mengetahui efektivitas antara dua metode (IM dan IU) dan faktor yang dapat mempengaruhinya pada sinkronisasi birahi sapi potong. Penelitian eksperimen ini mengunakan 60 ekor ternak sapi betina produktif yang diperoleh secara acak dan dibagi ke dalam dua kelompok, lalu disinkronisasi birahi (SE) menggunakan metode IM maupun IU. Parameter yang diamati yaitu lama kemunculan birahi berdasarkan bangsa ternak dan skor kondisi tubuh. Data hasil penelitian dianalisis mengunakan uji-t serta uji korelasi regresi. Hasil penelitian menunjukan bahwa sebagian besar sapi betina memberikan respons birahi terhadap pemberian preparat hormon PGF2α dan metode IM lebih lambat menimbulkan birahi dibandingkan dengan IU. Bangsa sapi Limosin metode IU memiliki rata-rata kemunculan birahi paling cepat dan yang paling lambat adalah bangsa sapi Bali metode IU. Nilai BCS memiliki korealsi yang nyata dengan respon birahi. Kesimpulan: secara teknis metoda IU lebih efektif dan efisien digunakan di lapangan. Kata Kunci: Birahi, Intra Muskuler, Intra Uteri, Sapi, SinkronisasiComparison of the efficiency of birahi synchronization with intra-muscular and intra-uterine methods using PGF2α in beef cattle ABSTRACT. This study aims to determine the effectiveness between the two methods (IM and IU) and the factors that can influence it on the estrus synchronization of beef cattle. This experimental study used 60 productive female cattle obtained randomly and divided into two groups, then estrus synchronized (SE) was carried out using the IM and IU methods. The parameters observed were the duration of the emergence of estrus based on the breed of livestock and body condition scores. The research data were analyzed using t-test and regression correlation test. The results showed that most of the female cows gave an estrus response to the administration of PGF2α hormone preparations and the IM method was slower to induce estrus than IU. The Limousine cattle breed with the IU method has the fastest average occurrence of estrus and the slowest is the Bali cattle breed with the IU method. The BCS value has a significant correlation with the estrus response. Conclusion: technically the IU method is more effective and efficient in use in the field.