Garlic (Allium sativum) contains a wide range of phytocompounds that produce various responses in human body. However the knowledge on the potential of fermented form of garlic in protecting negative impacts of radiation is very limited. In this research in vitro efficacy of fermented garlic in protecting negative impact of gamma ray was studied using cytogenetic test. A set of culture of human lymphocytes was irradiated with 60 Co gamma rays at dose of 2 Gy (dose rate of 2 Gy/min) and fermented garlic extract at four working concentrations of 0, 125, 250 and 500 mg/mL were added to these cells and then were incubated at 37 o C for 48 hrs. Colcemid was added at 3 hr before harvest to collect metaphase cells and it was done by standard methodology for cytogenetic analysis. The fermented garlic extract significantly (p<0.05) did not exhibited antigenotoxic effect of gamma rays and its effectiveness was same as in control (without extract treatment) group. In contrary all concentration of chemicals (125, 250 and 500 mg/mL) were seemingly tend to induce higher number of dicentric and fragment chromosomes than control under microscopic observation. Mitotic index of the cell that was determined with programmed metaphase finder also did not influenced by garlic addition. It was concluded that aqueous garlic extract did not possesses its efficacy in protecting impact of ionizing radiation.Keywords : fermented garlic, chromosome aberrations, genotoxic, ionizing radiation. ABSTRAKBawang (Allium sativum) mengandung berbagai macam senyawa fito yang menghasilkan bermacam respon dalam tubuh manusia. Akan tetapi pengetahuan tentang potensi bawang dalam bentuk fermentasi untuk melindungi efek negatif radiasi masih sangat terbatas. Dalam makalah ini kemampuan bawang fermentasi dalam melindungi efek negatif sinar gamma secara in vitro telah dipelajari menggunakan uji sitogenetik. Satu set kultur limfosit manusia diiradiasi sinar gamma 60 Co pada dosis 2 Gy (laju dosis 2 Gy/min) dan ekstrak bawang fermentasi pada empat konsentrasi kerja (0, 125, 250 dan 500 mg/mL) ditambahkan pada sel tersebut dan kemudian diinkubasi pada 37 o C selama 48 jam. Colcemid ditambahkan 3 jam sebelum pemanenan untuk mendapatkan sel metafase dan dilakukan dengan metodologi baku untuk analisis sitogenetik. Bawang fermentasi secara nyata (p<0.05) tidak menunjukkan kemampuan menekan dampak negatif sinar gamma dan efektivitasnya sama seperti dalam kelompok kontrol (tanpa pemberian ekstrak). Sebaliknya semua konsentrasi senyawa kimia (125, 250 dan 500 mg/mL) diduga cenderung menyebabkan jumlah kromosom disentrik dan fragmen yang lebih tinggi daripada kontrol pada pengamatan mikroskopis. Indeks mitosis sel yang ditentukan dengan programmed metaphase finder juga tidak dipengaruhi oleh penambahan bawang. Disimpulkan bahwa larutan ekstrak bawang tidak memiliki sifat melindungi dampak radiasi pengion.Kata kunci : bawang fermentasi, aberasi kromosom, genotoksik, radiasi pengion 116 Jurnal Ilmiah Aplikasi Isotop dan Radiasi