Pulmonary metastasectomy is undertaken for a range of cancers. The questions we raise here are specifically related to colorectal cancer, the commonest tumour for which pulmonary metastasectomy is undertaken. The primary objective of metastasectomy is to increase survival. There are no randomised trials in support of this practice nor are there any other forms of controlled studies. We present a critical look at the assumption of efficacy for this surgery and propose that a trial is needed and suggest a trial design.