Introduction: Breast cancer ranks second in the world and is the most frequent in women with 1.67 million new cases In 2012, it was 25% of all cancers, it is projected for 2030 more than 596,000 new cases and an increase of 142,100 deaths from breast cancer.One of the most frequent symptoms experienced by these patients is acute or chronic pain, which can occur at any time of the disease (Diagnosis, treatment, remission or relapse), should be evaluated and diagnosed, avoiding chronicity as much as possible.confers a degree of greater diffi culty for its control.Objectives: To determine the presence of pain in breast cancer patients undergoing cancer treatment (chemotherapy, radiotherapy, surgery, and / or hormonal treatment), and to describe the characteristics thereof.Methods: Descriptive cross-sectional study in patients attending the oncology service of San José Hospital with a diagnosis of breast cancer and who are undergoing oncological treatment through a personal survey.Results: Data were collected from 93 patients, of which 56.9% presented pain, with a higher prevalence of chronic pain in 52.8 %; 54.7 % classifi ed their pain as nociceptive and 45.2 % as neuropathic pain with intense pain in 49.0 %.The pain was treated in 52.8 % with acetaminophen, and 22.6% had no treatment.