Radiopharmaceuticals play an important role in modern nuclear medicine, and 18F-FDG (2-[18F] fluoro-2-deoxy-D-glucose) is the most frequently used in imaging examinations today. The pyrogen test represents an important parameter for the quality of radiopharmaceuticals since most of them, 18F-FDG included, are injectable solutions. However, the standard test proposed by the U.S. Pharmacopeia using limulus amebocyte lysates takes too long (about 1 h). An alternative test is the Portable Test System, which takes no more than 15 min. In order to compare both tests, 10 batches of 18F-FDG produced in the Nuclear Engineering Institute, Rio de Janeiro, Brazil, were analyzed. The results showed that in 40% of the samples analyzed, different results were found. From the total analyzed, 20% showed totally diverging results, and 80% demonstrated partial similarity. These differences have a great impact in the choice of the test used for radiopharmaceutical injectable solutions and the importance of validation tests before the implementation in the daily routine.