ABSTRAK Sinar-X merupakan radiasi pengion yang memiliki daya tembus yang cukup tinggi terhadap sel-sel tubuh organisme sehingga kerap digunakan dalam ilmu kedokteran. Selain memiliki manfaat, radiasi juga memiliki efek negatif terutama bagi sel tubuh. Tumbuhan waru (Hibiscus tiliaceus L.) telah lama digunakan masyarakat sebagai obat herbal dalam mengobati berbagai penyakit. Ekstrak metanol bunga waru (EMBW) diketahui memiliki aktivitas antioksidan yang dapat menangkal radikal bebas. Penelitian ini bertujuan untuk mengetahui potensi ekstrak metanol bunga waru terhadap perbaikan struktur jaringan hati mencit yang terpapar radiasi sinar-X. Rancangan penelitian yang digunakan adalah Rancangan Acak Lengkap (RAL), dengan 5 perlakuan dan 4 ulangan, yaitu K0 sebagai kontrol (akuades), K- (radiasi 65,45 mGy dan akuades), P1 (radiasi 65,45 mGy dan EMBW 0.79 mg/kg BB), P2 (radiasi 65,45 mGy dan EMBW 1,58 mg/kg BB), P3 (radiasi 65,45 mGy dan EMBW 0.79 mg/kg BB). Sinar-X dipaparkan sebanyak 6 kali dengan jeda sehari setiap pemaparan. Selang 14 hari dari pemaparan radiasi terakhir, hewan coba diberikan EMBW satu kali sehari selama 14 hari secara oral. Organ hati hewan uji dijadikan sediaan histologi dengan teknik parafin dan pewarnaan dengan Hematoksilin dan Eosin. Parameter yang diukur adalah jumlah proporsi sel hepatosit hati yang mengalami nekrosis dan degenerasi. Data dianalisis dengan menggunakan uji ANOVA dan dilanjutkan dengan uji berjarak ganda Duncan. Hasil penelitian ini menunjukkan bahwa EMBW mampu mengurangi jumah sel hepatosit yang mengalami nekrosis dan degenerasi akibat paparan radiasi sinar-X serta berpotensi sebagai hepatoprotektor. Kata kunci: Sinar-X, radiasi, Hibiscus tiliaceus L., bunga, Mus musculus L., hepatosit, hati, nekrosis, degenerasi. ABSTRACT X-rays are ionizing radiation which has a high enough penetrating power to the cells of an organism so that it is often used in medical science. Besides having benefits, radiation also has negative effects, especially for body cells. The waru plant (Hibiscus tiliaceus L.) has long been used by the public as a herbal medicine in treating various diseases. The flower of H. tiliaceus L. methanol extract (EMBW) is known to have antioxidant activity that can ward off free radicals. This study aimed to determine the potential of H. tiliaceus L. flower methanol extract to repair the liver tissue structure of mice exposed to X-rays. The research design used was a completely randomized design (CRD), with 5 treatments and 4 repetitions, namely K0 as a control (aquades), K- (65.45 mGy radiation and aquades), P1 (65.45 mGy radiation and EMBW 0.79 mg/kg BB), P2 (radiation 65.45 mGy and EMBW 1.58 mg/kg BB), P3 (radiation 65.45 mGy and EMBW 0.79 mg/kg BB). X-rays were exposed 6 times with intervals a day for each exposure. After 14 days from the last radiation exposure, the experimental animals were given EMBW once a day for 14 days orally. Liver of the experimental animals were made histological preparations with paraffin techniques and staining with Hematoxilin and Eosin. The parameters measured were the proportion of the amount of hepatocyte cells experiencing necrosis and degeneration. Data were analyzed using the ANOVA test and followed by Duncan’s Multiple Range Test (DMRT). The results of this study indicated that EMBW was able to reduce the number of hepatocyte cells experiencing necrosis and degeneration due to exposure to X-ray radiation and has the potential to be a hepatoprotector. Key words: X-rays, radiation, Hibiscus tiliaceus L., flowers, Mus musculus L., liver, hepatocytes, necrosis, degeneration.