A pictorial review of some of the complications of breast core biopsy is presented. Core biopsy of the breast is a commonly performed procedure that plays a vital role in the investigation of suspected breast cancer. Serious complications related to it are rare. The commonest problem is bleeding, which is usually easy to control at the time of the procedure. Arterial bleeding usually leads to the procedure being abandoned and repeated later. Applying pressure normally brings arterial bleeding under control within 15 min. Lesser degrees of haematoma can result in the lesion being obscured, which prevents a representative biopsy being obtained. In these cases repeat biopsy after an interval of 2 weeks allows the haematoma to resolve. Rarer complications of core biopsy include infection and abscess formation, pneumothorax, milk fistula formation, cosmetic deformity and seeding of tumour along the biopsy track. Complete removal of a mammographic abnormality such as microcalcifications can result in difficulty if localisation for excision is required.