Two newly bifunctional organoiron seleno-terephthalate derivatives (S1 and S2) were synthesized as potential anticarcinogenic compounds. In a previous study, they were found to have antibacterial and/or antifungal activity, while they did not show any mutagenic action. Such compounds were investigated in the present study for their antimutagenic activity. Sodium azide, hydrogen peroxide, and 4-nitro-o-phenylenediamine, as known mutagens for strains TA100, TA102, and TA98 of Salmonella typhimurium, respectively, were used. Both (S1 and S2) compounds showed a strong antimutagenic action of >98% against sodium azide, >70% against hydrogen peroxide, and >65% activity against 4-nitro-o-phenylenediamine. Bearing in mind the strong correlation between mutagenicity and carcinogenicity, the above compounds can be considered as potentially promising anticarcinogens. Therefore, the present results are very encouraging to investigate the above compounds for other biological activities, including their evaluation as anticarcinogens. A suggested mechanism for the antimutagenicity of the tested compounds is presented.