The peculiar properties of heavy fermion compounds at low temperatures combined with the lack of a comprehensive theory to consistently describe those properties have made the heavy fermions the subject of much study over the past few decades. For the first time, to our knowledge, magnetization measurements have been made on the heavy fermions Uranium Beryllium 13 (UBe13) and Praseodymium Beryllium 13 (PrBe13) at temperatures of 500 mK and to magnetic fields of 60 T. These experiments were carried out at the pulsed field facility at the National High Magnetic Field Laboratory at Los Alamos National Laboratories, Los Alamos, New Mexico. Measurements on both powder and single crystal samples of UBel3 reveal a slight temperature dependence and a Brillouin-like dependence on magnetic field. Measurements on PrBel3 powder also show Brillouin-like behavior, but exhibit no temperature dependence within experimental uncertainty. The data show no evidence for magnetic transitions in these materials.