The kind of salt used in doenjang preparation is one of the most important factors that affect the chemopreventive activities of doenjang. Bamboo salt (BS) is known to exert various therapeutic effects on several diseases. In this study, antimutagenic and anticlastogenic effects of methanol extracts of doenjang made with either one-time heat-treated BS (BS1-D), nine-times heat-treated BS (BS9-D), sun-dried salt (SDS-D), or purified salt (PS-D) using the Ames test and micronucleus test. BS1-D and BS9-D showed higher inhibitory effects than PS-D and SDS-D on mutagenicity induced by aflatoxin B(1), N-methyl-N'-nitro-N-nitrosoguanidine, and 4-nitroquinoline-1-oxide. BS1-D exerted more suppressive effects on chromosome aberration than SDS-D on mitomycin C-induced micronucleus in mice. It can be concluded that the chemopreventive effect of doenjang was significantly increased by using BS instead of the more typical commercial salts, SDS and PS (P < .05). This is probably due to the changes in the chemical and physical properties of the salt, especially increased content of K and P, during the processing of BS and to differences in fermented products formed during the doenjang fermentation in the presence of BS.