Standard options for advanced non-small cell lung cancer have focused on cisplatin-based regimens, including the combination of cisplatin with vinorelbine shown in randomized trials to be at least as effective as comparator regimens. Given its lower incidence of nonhematological toxicity, carboplatin may be an attractive alternative agent in combination with vinorelbine. To determine the tolerability of this regimen, a phase I/II study was conducted in 21 patients with stage IIIB/IV disease. A fixed dose of carboplatin (area under the concentration time curve = 2.5) was administered on days 1 and 8 q 21 days, together with vinorelbine also on days 1 and 8 at doses increasing from 20 mg/m2 to 25 mg/m2. This regimen was very well tolerated: only one case of grade 4 hematological toxicity and one case of grade 3 nonhematological toxicity occurred. Objective responses were seen. Given its tolerability and activity, the combination of carboplatin with vinorelbine at the doses and schedule studied should be further evaluated.