Due to hormone-induced physiological changes the diagnosis of breast cancer during pregnancy is challenging even for experienced radiologists. Sonography is the first choice procedure as the initial imaging modality for evaluating clinically symptomatic breasts during pregnancy. Mammography is an essential complementary imaging modality and is not regarded as an absolute contraindication in pregnancy. Image-guided percutaneous biopsy should be performed for immediate histological diagnosis of suspicious and unclear lesions. Contrast-enhanced magnetic resonance imaging (MRI) of the breast is of limited value in pregnancy. In cases of proven breast cancer complete local staging is recommended. If there is a high risk of distant metastases chest X-ray, ultrasound of the abdomen and plain MRI of the skeleton are recommended. Preoperative sentinel lymph node biopsy should be performed if indicated. Due to increased radiation exposure methods, such as bone scintigraphy and PET/CT should be avoided during pregnancy.