We conducted a phase I trial in advanced NSCLC to determine the optimal dosage of the new active drug paclitaxel (Taxol), in combination with high-dose ciplastin (CDDP). Taxol was infused over 3 h, followed by CDDP given over 30 min with hyperhydration. Main criteria of selection were the presence of metastatic or locally relapsing pathologically proven NSCLC, stage IIIB or IV and no prior therapy. Out of 17 treated patients, eight objective responses (47%) were documented. Significant but transient neutropenia was observed in steps III and IV. In seven patients, who received more than three courses, treatment was discontinued for severe polyneuropathy in five, cancer progression in one and unrelated disease in one. In conclusion, paclitaxel plus cisplatin, although active, was associated with severe late neurological toxicity prohibiting the administration of multiples courses.