Carboplatin is one of the most active agents in untreated small cell lung cancer (SCLC) (11% complete response [CR], 59% CR plus partial response [PR]). Combination carboplatin/etoposide/vincristine (CEV) (phase II trial) led to an overall remission rate of 84% in patients with limited disease (LD), with 52% CRs. The median survival time with this combination was 14 months in patients with LD and 9.5 months in those with extensive disease (ED). The 30-month survival rates are 30% in LD and 10% in ED, which represents a plateau of the survival curve. This regimen is highly effective and exhibits low toxicity in SCLC. To evaluate the role of carboplatin in combination chemotherapy in patients with extensive SCLC, a phase III trial was performed. In this ongoing trial comparing CEV and etoposide/vincristine in ED patients, CR and overall response rates to date are higher in the CEV arm (CR, 20% versus 15%; CR plus PR, 83% versus 65%), but as yet the differences are not statistically significant. In summary, chemotherapy regimens containing platinum compounds are among the most active in the treatment of SCLC. The use of the new compound carboplatin instead of cisplatin has led to similar or increased remission rates and is preferable because it has fewer side effects. Preliminary results from this ongoing, prospective, randomized phase III trial are presented.