This experiment was performed to evaluate the morphological responses of the appendicular mucosa of the mouse, inoculated with Ehrlich carcinoma cells in the inguinal area, following administration of BCG or CP-2 (Coptis chinensis-Croton tiglium extracts). Healthy adult ICR mice weighing 25 gm each were divided into normal and experimental groups (experimental control, BCG or CP-2 treated group). Each experimental group mouse was inoculated with 1 x 10(7) Ehrlich carcinoma cells subcutaneously in the inguinal area. From the next day after inoculations, 0.2 mL of saline, BCG (0.5 mL/25 g B.W.: 0.03 x 10(8) ~ 0.32 x 10(8) CFU) or CP-2 (30 mg/kg) were injected subcutaneously to the animals every other day, respectively. The day following the 7 th injection of BCG or CP-2, each mouse was injected with a single dose of 0.7 microCi/gm of methyl-3H-thymidine (25 Ci/mmol, Amersham Lab., England) through tail vein. Seventy minutes after the tritiated thymidine injection, animals were sacrificed. The number of the labeled epithelial cells of the appendicular mucosae were observed and evaluated. On histological studies of the experimental control, BCG or CP-2 treated mice, general morphologies of the appendicular mucosae were similar. On autoradiographic study, number of the labeled cells of normal control, experimental control, BCG treated or CP-2 treated groups were 362.2+/-56.12, 350.7+/-42.65, 265.8+/-27.08 and 241.3+/-53.29, respectively. Above results show that BCG and CP-2 suppress the DNA synthetic activity of the epithelial cells of the appendix, but did not show any remarkable morphological alterations on the mucosae. These results suggest that BCG and CP-2 are ones of effective anticancer drugs for the cytostatic therapy.