Pada pasien human immunodeficiency virus (HIV) positif, terapi antiretroviral (ARV) dapat berkontribusi terhadap kejadian ginekomastia. Ditemukan dua kasus ginekomastia pada pasien HIV di RS Pengayoman Cipinang antara tahun 2017–2019. Pada penelitian ini digunakan data yang diambil secara retrospektif dari rekam medis dan dianalisis menggunakan algoritma Naranjo. Kasus pertama, Tn. X, 34 tahun, diterapi dengan fixed-dose combination (FDC) berisi Tenofovir+Lamivudine+Efavirenz (TDF+3TC+EFV). Setelah dua tahun, kedua payudaranya membesar tanpa disertai nyeri. Terapi dengan TDF+3TC+EFV dilanjutkan selama 11 bulan, tetapi ukuran payudaranya tidak bertambah besar. Kasus kedua Tn. Y, 36 tahun, diterapi dengan Duviral (AZT+3TC)+EFV. Setelah 36 bulan, payudara kanan mulai membesar, tetapi tidak nyeri. Terapi dengan Duviral +EFV dilanjutkan selama dua tahun. Namun, ukuran payudara semakin membesar hingga diameternya 5 cm, keras, nyeri, tidak keluar air susu, dan tidak ada pembesaran kelenjar di ketiak. Oleh karenanya, EFV disubstitusi dengan Neviral. Setelah 12 bulan diterapi dengan Duviral+Neviral, terjadi regresi ginekomastia. Total skor Naranjo menunjukkan Tn. Y mungkin (probable) mengalami ginekomastia akibat EFV, sedangkan Tn. X cukup mungkin (possible) mengalami ginekomastia akibat EFV. Oleh karenanya, perlu dipertimbangkan substitusi EFV bagi pasien untuk menghindari penurunan tingkat kepatuhan minum obat akibat distres karena ginekomastia.Kata kunci: Antiretroviral, efavirenz, ginekomastia yang diinduksi obat, pasien HIV Gynecomastia Associated with Efavirenz: Report of Two Cases of HIV Patients AbstractThe antiretroviral (ARV) therapy administration is found to greatly contribute to gynecomastia incidence in human immunodeficiency virus (HIV) positive patients. Therefore, this study aims to determine the effects and characteristics of gynecomastia incidence among HIV patients receiving antiretroviral (ARV) therapy. Two gynecomastia cases were found among HIV patients at Cipinang Pengayoman Hospital in the year 2017–2019. In this study, data were collected retrospectively from medical records and analyzed using the Naranjo algorithm. The first case, Mr. X, 34 years old, was treated with a fixed-dose combination (FDC) containing Tenofovir+Lamivudine+Efavirenz (TDF+3TC+EFV). After two years of therapy, there was breasts enlargement without pain. Then, the TDF+3TC+EFV therapy continued for 11 months, however, no changes was observed. The second case, Mr. Y, 36 years old, was being treated with Duviral (AZT+3TC)+EFV. After 36 months, the right breast began to enlarge without pain, then, the Duviral+EFV therapy continued for two years. However, the breast size was getting bigger until it was 5 cm in diameter, hard, painful, without milk, and no enlargement of the glands in the armpit. Then, the EFV was substituted with Neviral, after 12 months of Duviral+Neviral therapy, gynecomastia regression occurred. The Naranjo total score indicated that Mr. Y probably experienced gynecomastia due to EFV, while Mr. X possibly experienced gynecomastia due to EFV. Therefore, it is necessary to consider EFV substitution for the patient to avoid decreased adherence, resulting from the distressing side effect of gynecomastia.Keywords: Antiretroviral, drug-induced gynecomastia, efavirenz, HIV patient