Nineteen previously untreated patients with colorectal cancer and measurable disease were treated with iproplatin (CHIP), 75 mg/m2 daily, for 5 days every 4 weeks for at least 2 courses. Toxicities included myelosuppression, mild nausea and vomiting, and rare mild nephrotoxicity. The dose-limiting toxicity was thrombocytopenia, which appeared to be cumulative. Dose reduction was frequently necessary. There were no toxic deaths. One partial response was observed, and four patients had stable disease for a median of 2 months. Iproplatin does not appear to have significant activity against colorectal cancer.