Cyclooxygenase-2 (COX-2) overexpression is seen in many malignancies including lung cancer. Elevated tumor prostaglandin E2 (PGE2), a major COX-2 metabolite, levels have been implicated in angiogenesis, tumor growth and invasion, apoptosis resistance and suppression of anti-tumor immunity. Recent studies also revealed that PGE2 signaling may confer cells resistant to targeted growth factor receptor therapy by cross-activation of the receptor signaling pathway downstream components. Pre-clinical studies in animal tumor models have shown tumor reduction when animals are treated with COX-2 inhibitors and have demonstrated promising results when COX-2 inhibitors were combined with chemotherapeutic drugs. Based on these observations several ongoing clinical trials are currently evaluating COX-2 inhibitors as adjuvants with chemotherapy or radiation therapy in patients with advanced non-small cell lung cancer. Further understanding of the mechanisms of COX-2 in tumorigenesis and its interaction with other cellular pathways may highlight the new diagnostic, prognostic and therapeutic markers and facilitate future development of targeted strategies for lung cancer treatment and prevention.