The liver is the exclusive site of metastasis in approximately 30% to 50% of patients with stage IV colorectal cancer, whereas lung metastasis occurs in 10% to 20% of patients. No single study has specifically addressed the predictors of survival after resection of synchronously diagnosed lung and liver metastases. Patients who undergo metastasectomy for simultaneous lung and liver metastases have a reported 5-year survival rate of approximately 40%. The prognostic significance of simultaneous presentation of lung and liver metastases (versus temporally separated presentations) is unclear. Other proposed predictors include short disease-free interval, patient age, and lung as first metastatic site. A paucity of data has led to a clinically driven treatment approach that recognizes the survival benefit for complete resection of disease, particularly when disease responds to systemic chemotherapy. Simultaneous or sequential resection of liver then lung metastases enables good long-term survival. © Springer Science+Business Media, LLC 2010.