It is well known that the magnetic properties, such as the Curie temperature, Tc, and the mean magnetic moment, β, of the ordered compounds differ from those of the disordered state. For instance, both Tc and β of the Ni₃Fe (L1₂) ordered compounds are higher than those of the disordered Fe-Ni alloys. On the other hand, Tc of the Fe₃Al (D0₃) ordered compound is depressed from that of the disordered Fe-Al alloys. In consequence, the stability of the ordered phase is enhanced or depressed due to the interaction between the chemical and magnetic ordering caused by the increase or decrease of Tc and β. The purpose of this study is to investigate the quantitative effect of the interaction of the B2 (FeAl, FeCo, FeGa and FeSi), D0₃ (Fe₃Al, Fe₃Ga and Fe₃Si) and L12 (Ni₃Al) ordered configurations. Taking the interaction effect into account, thermodynamic assessment of the Fe-X (X=Al, Co, Ga, Ni and Si) alloys was carried out. Following suggestions were obtained from the result of thermodynamic analysis: (1) the anomalous A2+B2 two-phase separation in the Fe-Al and Fe-Ga systems is caused by the depressive interaction between the B2 chemical and magnetic ordering. (2) The stability of the B2 ordered configuration in the Fe-Co system is mostly caused by the enhancive interaction effect. (3) The stability of both Ni₃Fe (L1₂) and FeNi (L1₀) compounds is strongly enhanced by the additional magnetic energy due to the chemical ordering. The calculated phase diagram indicates that the FeNi (L1₀) phase is stable.