Paclitaxel is a new antineoplastic agent with activity in lung cancer. This phase I clinical trial was designed to determine the maximum tolerated dose (MTD) of paclitaxel in combination with etoposide in previously untreated patients with non-small cell lung cancer (NSCLC). Doses of paclitaxel were in the range of 150-225 mg/m2 (d1) and of etoposide in the range of 100-120 mg/m2 (d2-4). The drugs were administered by i.v. infusion over 3 h (paclitaxel) and 2 h (etoposide). The patients received four courses at 21-day intervals. Twenty-four patients (six female, 18 male) entered the trial. The characteristics of the patients were as follows: median age 64 (55-73) years; Karnofsky index 80% (70-90%); stage IIIB n = 7, IV n = 17; histology, 14 adenocarcinoma, 10 squamous carcinoma. Hypersensitivity reactions after paclitaxel were not observed. The most relevant toxic effect observed was neutropenia (WHO grade 3-4). Three episodes of febrile neutropenia, two episodes of absolute neutropenia (< 100/microliter for > 3 days), and one case of mucositis (WHO grade > or = 3 for > 7 days) occurred. It can be concluded that the MTD of paclitaxel in combination with etoposide was reached at doses of 200 mg/m2 paclitaxel (d1) and 100 mg/m2 etoposide (d2-4).