Abstract: This investigation concerns with the potential adverse biological effects of subchoronic exposure of male rats to low intensity Static Magnetic Field (SMF) on the biophysical properties of hemoglobin (Hb) molecule as well as possible genotoxic effects on DNA stability. Animals were equally divided into four groups: control group and three groups exposed to 3 mT SMF for different time intervals, the last group was used for delayed effect study. The viscometric and refractometry measurements for Hb (intrinsic viscosity, Huggins coefficient, slope and refractive index) as well as the DNA alteration in somatic and germ tissues using Random Amplified Polymorphic DNA (RAPD) method were carried out for all groups. The results revealed a remarkable change in viscometric and refractometry measurements in exposed animals indicating change in the molecular shape and dimensions of Hb and its protein conformation. Also, the data indicated changes in RAPD profiles in DNA isolated from germ tissue in exposed animals. In contrast the same treatment failed to induce DNA damage in somatic tissue. The results showed the dependence of SMF biological effect on the period of exposure. The data also revealed no sign of changes in all studies carried out on Hb and DNA for animals of delayed effect experiment indicating that the damage induced in Hb molecule and DNA isolated from testis were fully recovered or repaired and/or non cumulative effect of magnetic field.