Latar Belakang: Nyeri tenggorokan pasca operasi merupakan efek samping yang sering terjadi pada pasien yang menjalani operasi dengan anestesi umum dan menduduki peringkat kedua terbanyak. Insiden terjadinya nyeri tenggorokan pasca operasi bervariasi dari 20.4%-75%. Salah satu faktornya yaitu ukuran selang endotrakeal dan beberapa penelitian sebelumnya menyatakan bahwa terdapat hubungan antara ukuran selang endotrakeal dan nyeri tenggorokan pasca operasi. Tujuan : Untuk mengetahui hubungan antara ukuran selang endotrakeal dengan nyeri tenggorokan pasca operasi dengan anestesi umum di Rumah Sakit Umum Siloam Lippo Karawaci. Metode: Penelitian ini menggunakan studi potong lintang pada 106 responden. Pengambilan data dilakukan dengan metode wawancara medis dan pengambilan data rekam medis. Pengambilan sampel dilakukan secara convenience. Data dianalisis di SPSS 25.0. Hasil Analisis Data: Dari hasil penelitian ditemukan bahwa terdapat hubungan antara ukuran selang endotrakeal dengan nyeri tenggorokan pasca operasi dengan insiden sebesar 63.2% (n=67). Insiden terjadinya nyeri tenggorokan pasca operasi terbagi berdasarkan kategori sebagai berikut: Ukuran 6.5 ID sebesar 1.9% (n=2), ukuran 7.0 ID sebesar 24.5% (n=26), ukuran 7.5 ID sebesar 32.1% (n=34), dan ukuran 8.0 ID sebesar 4.7% (n=5).Hasil p-value sebesar 0.044 pada uji chi-square. Simpulan: Terdapat hubungan antara ukuran selang endotrakeal dengan nyeri tenggorokan pasca operasi di Rumah Sakit Umum Siloam Lippo Karawaci / Background : Postoperative sore throat is one of the most common side effect that occurs in patient underwent surgeries under general anesthesia and become the second most complications occur. The incidence of postoperative sore throat ranging between 20.4% - 75%. One of the factors involved is the size of endotracheal tube and studies found a relationship between post-operative sore throat and endotracheal tube. Aims : This study aims to find the relationship between the size of endotracheal tube and postoperative sore throat at Rumah Sakit Umum Siloam Lippo Karawaci. Methods : This study is a cross sectional study in 106 post-operative patient under general anesthesia at Rumah Sakit Umum Siloam Lippo Karawaci. Data was collected by interview and assess medical record. Sample was taken by convenience sampling method. Data was analyzed using SPSS 25.0. Results : There is a relationship between the size of endotracheal tube and postoperative sore throat. The incidence of post-operative sore throat was 63.2% (n=67). The incidence of post-operative sore throat based on size of endotracheal tube: 6.5 ID in size was 1.9% (n=2), 7.0 ID in size was 24.5% (n=26), 7.5 ID in size was 32.1%(n=34), 8.0 ID in size was 4.7% (n=5). Analysis using chi-square showed p-value of 0.44. Conclusion : There is a relationship between the size of endotracheal tube and post-operative sore throat in Rumah Sakit Umum Siloam Lippo Karawaci.