The antimutagenic and anticancer effects of baechu cabbage (Brassica campestris L. ssp pekinensis [Lour.] Rupr.) cultivated in Noji and Tunnel in spring were investigated under in vitro and cellular system using HT-29 human colon carcinoma cells. Proximate composition, mineral and vitamin contents of baechu cabbages (Noji and Tunnel) were evaluated. Antimutagenicity were measured in Ames test using N-methyl-N`-nitro-N-nitrosoguanidine (MNNG) and aflatoxin B1 (AFB1). The viability and growth of HT-29 cells were evaluated by MTT (3-(4,5-dimethyl-thiazol)-2,5-diphnyltetrazolium bromide) assay and growth inhibition test, respectively. The gene and protein expressions of apoptosis-related proteins such as Bax, Bcl-2, p53 and p21 were investigated by reverse transcription-polymerase chain reaction (RT-PCR) and western blot. The contents of carotene, Ca, K in Tunnel baechu cabbage (Tunnel) were higher than those of Noji baechu cabbage (Noji). The methanol extract from the spring baechu cabbage particular cultivated by Tunnel method effectively reduced mutagenicity induced by MNNG. The Tunnel also showed higher antimutagenic effects against AFB1 than the Noji. The HT-29 cells showed the significant decreases in cell viability by the treatment of the Tunnel with dose-dependence in MTT assay. The Tunnel also inhibited on the growth of HT-29 cells in a time-dependent manner. The baechu cabbage induced apoptosis in HT-29 cells were associated with the decreased expression of the anti-apoptotic Bcl-2 and increased expression of p53, p21 and Bax. The present study suggests that the baechu especially the Tunnel would have increased antimutagenic effect and anticancer activity through induction or repression of apoptosis. (Cancer Prev Res 13, 122-129, 2008)