BACKGROUND: Core needle biopsy (CNB) is often the initial test for polyadenopathic syndrome and is usually performed by radiologists. The objectives of this study are to determine the diagnostic yield of ultrasound-guided CNB of lymph nodes performed by internists at a tertiary care hospital, the most frequent etiological diagnoses, and the safety of this technique. MATERIALS: Observational, descriptive study in which we included all patients over 17 years of age who had undergone ultrasound-guided CNB of lymphadenopathy by a member of the internal medicine service of the Virgen del Rocío University Hospital in Seville from 2021 to 2023. RESULTS: A total of 76 patients were included, 49 (64.5%) were male and the median age [IQR] was 64 [42-75] years. The most frequent location of lymphadenopathy was inguinal (38.2%). This test allowed a definitive diagnosis in 71 (93.4%) of the patients. Of the 5 in whom the diagnosis was not reached by the CNB, three required an open biopsy, one was diagnosed with Bartonella henselae by serology and in a fifth the diagnosis was not reached. The median delay for the BAG[IQR] was 1[0-3] days. No patient had complications. The most frequent diagnosis was lymphoma in 31 (41.8%) patients. CONCLUSIONS: Ultrasound-guided CNB performed by internists is a safe, feasible test with very little delay. These data support the extension of this practice to the rest of the internal medicine services.