Background: Emergency department (ED) visits are a distressing event for patients with advanced cancer, and identifying planned, unplanned and avoidable ED visits is important for providing better cancer care. We studied the causes for ED visits, as well as potentially avoidable ED visits during palliative chemotherapy, among patients with advanced cancer treated at a public cancer center in Mexico City. Methods: Consecutive patients with newly diagnosed advanced solid tumors treated at Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán from 10/2015 to 03/2016 were screened. Patients who visited the ED during that period were included, and their demographic and clinical characteristics recorded. Number and reasons for ED visits were obtained from medical records. Among patients who received chemotherapy within the previous 30 days, the following reasons for ED visits were classified as avoidable: anemia, nausea, dehydration, neutropenia, diarrhea, pain, emesis, pneumonia, fever or sepsis (according to Centers for Medicare and Medicare Services Hospital Outpatient Quality Reporting Program). Results: 77 patients were diagnosed with advanced solid tumors during the study period, of which 53 (69%) had at least one ED visit. Median age was 63 years (range, 19-88), and 47% were men (n = 25). 51% had gastrointestinal, 21% genitourinary and 28% other tumors. Median follow-up was 360 days. 95 ED visits were identified; with a median number of ED visits per patient of 1 (range 1-5). The most common causes of ED visits were: infections (n = 20; 21%), gastrointestinal disorders (n = 18; 19%), pain (n = 15; 16%), ascites (n = 14; 15%), anemia (n = 4; 4%), catheter dysfunction (n = 4; 4%), and other causes (n = 20; 21%). 57% of ED visits among patients who received chemotherapy within the previous 30 days were classified as potentially avoidable. Conclusions: Over two thirds of patients with newly diagnosed metastatic cancer had ED visits in the first year after diagnosis. Furthermore, more than a half of ED visits among patients receiving palliative chemotherapy were potentially avoidable. Strategies aimed at reducing ED visits are needed to improve quality of care for patients with advanced cancer.