Antimutagenic and anticarcinogenic effects of doenjang(Korean fermented soy paste) were studied by using Ames test(Salmonella typhimurium assay system) and C3H/10T1/2 cells, respectively. Doenjang(traditionally or commercially prepared) exhibited strong antimutagenic activity compared to chongkukiang and miso against aflatoxin B, (AFB, ) and N-methyl-N'nitro-N - nitrosoguanidine (MNNG )
The soybean and soybean+flour(7 : 3) which were used raw materials for doenjang prepara-tion showed lower antimutagenic activity compared to the fermented soybean, deenjang. It seemed that antimutagenic compounds are released or made during the long period of the for-mentation, and the raw material of soybean for making doenjang are the main source to in-crease the antimutagenicity.
Doenjang considerably decreased the cytotoxicity induced by carcinogen, 3-methylcholan-threne(MCA) in C3H/10T1/2 cells, showing that doeniang protected cells against harmful ef-fect due to the carcinogen in cells in vitro. The type II and type III foci formations from the MCA treatment were also significantly decreased when the methanol extract of doeniang added to the C3H/10T1/2 cells, indicating that doenjang could Prevent the carcinogenicity me-diated by MCA.
From the experiments, doenjang efficently prevents the mutagenicities induced by mutagens/carcinogens, and decreased transformation of the cells by a carcingen.

Keywords: Doenjang, Antimutagenicity, Ames test, Anticarcinogenicity, C3H/10T1/2 cells