Six patients with peritoneal carcinosis and ascites received 13 courses of ip cis-platinum (c-DDP). C-DDP (170-250 mg in 2L saline, dwell 4 h) was administered via Pig-Tail-Cordis catheter with concurrent infusion of sodium thiosulfate (bolus 7.5 g/m2 followed by 2.13 g/m2/h for 12 h). The patients received pre- and post-therapy hydration (250 ml/h) and mannitol-induced diuresis. Courses were given in 4 weekly intervals. With a dwell time of 4 h 27.0% +/- 14.6% (mean +/- SD) of platinum were recovered. Total serum platinum peaked at 3.1 +/- 1.0 microgram/ml. The peritoneal/serum ratio of platinum concentration was 49.5 +/- 12.6 after 1 h, 7.4 +/- 1.7 after 5 h and 4.2 +/- 1.7 after 12 h. Within 12 h 30.9% +/- 10.0% of the administered dose were excreted in urine. In 4 patients the ascites had disappeared lasting 14+, 15+, 5+, 3+ months. 2 patients died within 1 month caused by systemic tumor progression. Following toxicity was observed: 9/13 nausea and vomiting grade 1 (WHO), 2/13 hematological toxicity grade 2, 1/13 sterile peritonitis, no renal or neurological toxicity. This pilot study demonstrates a pharmacokinetic advantage of ip chemotherapy with c-DDP and an effectiveness against peritoneal carcinosis.