In a multicentre trial of the EORTC ECTG we have treated 43 non-pretreated patients with advanced non-small-cell lung cancer (NSCLC) with the new semisynthetic taxoid docetaxel (Taxotere). Six patients were ineligible; of the 37 eligible patients, ten had prior radiotherapy and 18 prior surgery. They received 100 mg m-2 in 1 h i.v. every 3 weeks, usually in an outpatient setting. Prophylactic steroids, antihistaminics or antiemetics were not routinely given. Two patients were not evaluable because they withdrew from the study because of a hypersensitivity reaction after the second cycle. The main toxicity was neutropenia (80% of cycles), although infections were rare (4%). One patient died from sepsis during neutropenia. Hypersensitivity reactions necessitating interruption of docetaxel (Taxotere) infusions were found in only 10% of cycles. The overall response rate was 23% with one complete response, and seven partial responses. Stable disease was found in 16 patients. The median duration of response was 36 weeks, and the median survival of all patients was 11 months. Docetaxel (Taxotere) is among the most active drugs for treatment of NSCLC.