Results of measurement between 746 and 1231 ‡C of the diffusion coefficient Fe-59 in the Fe-17·6 at.% V alloy, together with Mirani's et al., Lai-Borg's and Hettich's et al. data analysis, are presented. All the data show a marked ferromagnetic effect, i.e. the lnD(T) values measured at the temperaturesT<θ are distinctly lower than those extrapolated by the linear Arrhenius plot from the paramagnetic range. The results are interpreted in terms of the Heisenberg model, Kirkwood's and Girifalco's statistical theories. The computer fit of an analytical form, derived for the excess activation enthalpyδH(T), to experimental data enabled us to calculate the values of the exchange integralJ 0 and the paramagnetic temperatureT p. The corresponding values for the Fe-17·6% V alloy are:J 0=(315±11)k,k is the Boltzmann constant, andT p=(1223±±18) K. The activation enthalpy of Fe self-diffusion in a completely ordered ferromagnetic Fe-17·6% V matrix is higher by the value ofδH(0)=(55·2±1·9)kJ/mol than the value 236·35 kJ/mol corresponding to a fully paramagnetic state. Applying a three paramagnetic fit to Mirani's, Lai-Borg's and Hettichs data, we have found that the ratio of the vacancy migration enthalpy and of the formation enthalpy in α-Fe, in Fe-17·6% and Fe-7·64% Si, may be expressed by the valueH M/H F=1·62 ± 0·18. A comparison ofJ 0(α-Fe) toJ 0(17·6 %V) and toJ 0(7·64% Si) shows that the magnetic dilution caused by 17·6% of vanadium is negligible withJ 0(17·6% V)/ /J 0(α-Fe)=0·999. The dilution brought about by silicium is by about 1·24 times higher, and the ratioJ 0(7·64% Si)/J 0(α-Fe)=0·86. The paramagnetic temperatures in the materials under study are given by the relationT P=(gQ + 137) K,θ being the respective Curie-temperature. The present analysis makes it possible to calculate the Fe diffusion characteristicsD 0f aH f in a fully ordered magnetic matrix.