We described a 70 years old patient with pericardial effusion due to adenocarcinoma of the lung, in whom gefitinib, which is an oral selective inhibitor of the epidermal growth factor receptor of tyrosine kinase, demonstrated a marked antitumor effect. We recommend possible consideration of a treatment with gefitinib for female patients with pericarditis carcinomatosa due to lung adenocarcinoma, even if they have a poor performance status and are not indicated for other intensive therapy.