Lung cancer remains a significant cause of mortality worldwide. While advances in therapy continue to be made, the overall prognosis for patients diagnosed with lung cancer remains poor. Historically, markers such as age, performance status and disease stage have been used to risk-stratify patients and guide therapeutic decisions. These parameters provide some useful information, but more sensitive markers are clearly needed. Molecular and genetic studies have identified several such markers, which appear to play critical roles in carcinogenesis and affect patient outcomes. This article reviews a number of biomarkers that have been identified in lung cancer, and their prognostic and predictive roles.