Stannous chloride (SnCl2) has been used in many sectors of human activities such as food manufacturing and in nuclear medicine to produce radiopharmaceuticals labeled with technetium-99m (99mTc). Due to its importance and genotoxic potentiality, we decided to evaluate the biological effect induced by a nuclear medicine kit, which includes SnCl2, in association with glucoheptonic acid (GHA) which is employed for brain and renal scintigraphies. These studies were carried out with the Escherichia coli AB1157 strain and the deoxyribonucleic acid (DNA) plasmid pUC 9.1. The experiments, with different concentrations of SnCl2 and GHA, show an inverse relationship between both agents. When the GHA concentration was increased, the cellular inactivation induced by SnCl2 was reduced, as measured by the number of viable cells. Moreover, GHA protects the DNA molecule against the damage induced by SnCl2.