Non-invasive and hazard-free methods for diagnosing malignant lymphomas are represented by scintigraphy with gallium 67 and by lymphoscintigraphy, especially of the retroperitoneum. These methods are particularly suitable for closely following up the course of the disease. In this article, radiopharmacology, pharmacokinetics and techniques of examination associated with these methods, are described, and typical findings are demonstrated by means of clinical case examples. Attention is also paid to radiation exposure load. The ranking of these methods within the framework of x-ray diagnostics, is also discussed.