To assess the efficacy of carboplatin when used as a single agent in patients with advanced non small cell lung cancer (NSCLC) and who are refractory to chemotherapy with a non-platinum combination, we recruited patients (n=40) NSCLC patients, 36 of whom were males, with an overall median age of 59 years (range 39-79) and Karnofsky Performance Status of 70% (range 60-90%). At baseline, the patients had a median of one disease site (range 1-3) and had received a median of one prior regimen (range 1-2). Carboplatin was administered (i.v.; AUC=6) every 3 weeks until disease progression or non-acceptable toxicity was reached. In total 169 cycles were administered (median 4 cycles/patient; range 1-8). Main toxicities were grade 2-3 anemia and grade 4 thrombocytopenia (22.5% of patients). Overall clinical response rate was 10% (4 partial responses); 26 patients (65%) had stable disease and 8 (20%) had disease progression. Median time to progression and median survival time were 90 and 187 days, respectively. One year survival rate was 13%. We conclude that carboplatin shows minimal toxicity with a discrete anti-tumor activity in patients with NSCLC and who are refractory to non-platinum combinations.