SummaryA biopsy involves close co‐operation between a surgeon and a pathologist if a representative piece of tissue is to be obtained, and diagnosed.The surgeon must appreciate the limitations placed on the pathologist as he examines many tissues at an early stage of disease.The pathologist must seize every opportunity of correlating his histological evidence with the clinical history, X‐ray appearance, other laboratory investigations, and the ultimate course of the disease.Only in these ways can the patient benefit to the full from a bio