The purpose of this study was to evaluate the relationship between proliferation and cell death during oral carcinogenesis. Syrian golden hamsters which were 3 month old and 90-120 gm-weight were used in this study. The 9, 10-dimethyl-1, 2-benzanthracene(DMBA) in a 0.5% solution in mineral oil was painted on the buccal pouch mucosa 3 times per week in the experimental group during 20 weeks. Control group was painted with mineral oil. In each control and experimental group of 6,8, 10, 12, 14, 16, 18,20 weeks, specimen were sectioned for immunohistochemical study with anti-Proliferating Cell Nuclear Antigen(PCNA), anti-transglutaminase transglutaminase and GST-pi were obtained by counting the positive cells to those antibodies. The following results were obtained. 1. Histopathologically, finding of epithelial dysplasia of the 6 and 8 weeks experimental group and carcinoma in situ in the 12 weeks and squamous cell carcinoma in those of the 14 weeks were seen. 2. PCNA positive cells were mainly mild expressed in the basal cell layer of normal oral mucosa, increased moderately, after 6 weeks. In suprabasal cell layer, control group is negative but retained moderately between 6 weeks and 14 weeks, and decreased after 16 weeks. In spinous cell layer, restricted only between 12 weeks and 16 weeks, other period is mild or negative. 3. PCNA index of experimental group revealed the increased peak in 6 weeks and 20 weeks than control group, and retained between 12 weeks and 18 weeks. All experimental group expressed higher PCNA index than control group(p.<0.05). 4. Tranglutaminase expression was localized in outer and suprabasal layers on control group, but after 6 weeks, expression site moved spinous & suprabasal cell layers, and after 8 weeks, expression is spreaded to basal cell layer, and this patters retained to 20 weeks. Transglutaminase expression of experimental group was higher than control group after 8 weeks. 5. The positive staining of detoxifying agent, G1utathione S-Transferase(GST)pi of experimental group was radually increased from 6 weeks. After 10 weeks, all layer of experimental group was seen positive reaction. The strong positive staining in center of tumor and weak positive staining in periphery of tumor were seen at the stage of squamous cell carcimoma in 14 weeks. According to the results, we should suggest that the more increased proliferation of tumor cell, the more increased expression of PCNA, transglutaminase and GST-pi as a detoxifying agent during carcinogenesis by induced DMBA were seen.