BACKGROUND:The clinical impact of c-erbB-3 has seldom been assessed in patients with non small cell lung cancer (NSCLC). PATIENTS AND METHODS:Forty-three NSCLC patients treated by erlotinib for c-erbB-3 and EGFR expression were investigated by immunohistochemistry analysis. RESULTS:Two partial responses, one minor response, two stable diseases and twenty progressive diseases were observed at the first evaluation. Seventeen patients died before evaluation. Median EGFR expression was 70% of the cancer cells. Forty-two percent of the tumours co-expressed c-erbB-3 and EGFR without any difference according to histology or disease stage. There was no correlation between c-erbB-3 and EGFR expression. Median survival time was 2.6 months and the six months survival rate was 21%. There was no detectable impact of EGFR (p=0.94) or c-erbB-3 (p=0.93) expression on survival. CONCLUSION:In this small particular cohort of NSCLC patients receiving salvage therapy with erlotinib, there was no correlation between c-erbB-3 expression and clinical parameters, nor between cerbB-3/EGFR expression and outcome.