Mutagenicity and cytotoxicity of fresh juice and alcohol extract from garlic were studied by Ames' test, Rec assay, Micronucleus test and the check of the influence to HEp 2 and chinese hamster embryo (CHE) primary cultured cells. No evidence of mutagenicity of these samples were observed in Ames' test and Rec assay, while there was dose dependent increase of micronucleated cells and polychromatocytes on the bone marrow cells of mice and chinese hamsters treated with garlic juice. There were severe damages, e.g. growth inhibition and morphological changes of both cultured cells due to garlic juice, but no or slightly cytotoxic signs were observed even in high concentration of garlic extract. A higher sensitivity to the cytotoxic effects of garlic was seen by the present findings with CHE primary cells than HEp 2 cell line.