In order to know the normal distribution of trace elements is rats, in terms of age, we have determined the elemental composition
of different organs and body tissues by neutron activation analysis following an animal experiment during which the rats raised
outside of any kind of pollution, were fed with a defined diet. The values observed for Co, Zn, Mn, Se, Fe, Cs, Rb, Hg, Cd
in heart, body muscles, liver, kidney and testis are represented in table and figures. Except for renal accumulation of Hg
and Cd, the more interesting fact revealed in this work, in the accumulation of Fe in body muscles and testis.