Erlotinib is an orally available, reversible tyrosine kinase inhibitor of the epidermal growth factor receptor. Encouraging activity as a single agent and in combination with other targeted agents has been demonstrated in Phase II trials in many tumour types. Erlotinib has an established role in the treatment of advanced, refractory non-small cell lung cancer-based on a pivotal trial demonstrating a survival advantage over best supportive care. In a Phase III trial, the addition of erlotinib to gemcitabine improved survival in advanced pancreatic cancer. The toxicity profile of erlotinib includes diarrhoea and rash, with no haematological side effects. Predictive factors for response include the presence of a rash, epidermal growth factor receptor expression and mutation status. This article reviews the current clinical status of erlotinib.