The advent of radiologic guidance techniques for percutaneous biopsy has changed the approach to the routine diagnosis of mediastinal lymphoma. The aim of the present study was to evaluate the diagnostic accuracy of CT-guided percutaneous core-needle biopsy (PCNB) in the clinical management of patients with mediastinal lymphoma. The results of 49 CT-guided PCNB of mediastinal lymphoma performed under local anesthesia in 42 ambulatory patients were analyzed. A positive diagnosis of lymphoma was obtained in 30 of 42 patients, with an overall success rate of 71.5%. The technique was equally successful in the diagnosis of Hodgkin's and non-Hodgkin's lymphoma. There were no major complications. Percutaneous CT-guided CNB of mediastinal lymphoma is a quick, safe, accurate, and efficient alternative to open biopsy in the evaluation of mediastinal lymphoma, mainly at presentation. It should become the preferred initial diagnostic procedure for obtaining histologic samples in patients with suspected mediastinal lymphoma.