Acute generalized exanthematous pustulosis (AGEP) is a rare acute reaction that is drug induced in 90% of the cases and characterized by a widespread, sterile pustular rash. Erlotinib, a small-molecule EGFR tyrosine kinase inhibitor, has been approved by the FDA for patients with pancreatic cancer and non-small cell lung cancer. Skin rash is a well-known side effect related with all EGFR blocking agents. It has been suggested that rash could be used as a surrogate marker for response and possibly be associated with prolonged survival. We report a case of rare presentation of AGEP involving an adverse effect of erlotinib. The commonly reported adverse effects of erlotinib are mild skin eruptions. However, our case describes the rare presentation of AGEP induced by erlotinib. The estimated incidence rate of AGEP is approximately 1–5 cases per million/year.