Animal models are useful in the evaluation of adjuvant or palliative treatment modalities of human colonic adenocarcinoma. In the present paper, the efficacy of 22 usual chemotherapeutic agents was evaluated in a model of peritoneal carcinomatosis of colonic origin in the BD IX rat. Mitomycin, cisplatine, carboplatine, cyclophosphamide, ifosfamide, and thiotepa were very effective agents on microscopic carcinomatosis (treatment given 3 days after an intraperitoneal inoculation of 1 x 10(6) DHD/K12/PROb cells). Intravenous administration was as effective as the intraperitoneal route, except for anthracyclines and 5-fluorouracil. Rats treated at early stages by thiotepa or cisplatin survived up to 4 months after cell injection and did not display tumor at autopsy. Administered late (15 days after cell injection), none of the drugs were able to cure the rats with carcinomatosis.