Garlic (Allium sativum L.) with the food supplement material and medicine was used traditionally in Asia and Europe. Epidemiological studies revealed that the intake of garlic reduced incidences of various cancer including digestive system. The present study was designed to investigate the effect of garlic ethanol extract on the development of colonic aberrant crypt foci (ACF) induced by 1,2-dimethylhydrazine (DMH) in male F344 rats. Five-week-old rats were given four times for two weeks to subcutaneous injections by DMH (30 mg/kg body weight) to induce ACF. The animals were divided into groups that fed diet containing garlic ethanol extract at five different doses (0.1, 0.2, 0.5, 2, 5%), respectively, animals were evaluated for the total number of ACF and total aberrant crypts (AC) per colon detected from methylene blue-stained rat colon. ACF were formed in animals in DMH-treated group. The feeding suppressed potently the appearance ACF in the colon of rats. Especially, fed diet containing garlic ethanol extract at intermediate dose (0.5%) significantly reduced the number of ACF and AC per colon (p < 0.05). Garlic ethanol extract inhibited DMH-induced overexpression of Activator Protein-1 (AP-1) and ${eta}-catenin$ genes related to cell proliferation that also upregulated the expression of p21Waf1/Cip1 mRNA, a cell cycle-regulating gene. These results suggested that garlic ethanol extract may inhibit ACF formation, ${eta}-catenin$ gene as the early preneoplastic marker of malignant potential in the process of colon carcinogenesis.