In this paper, we report on a theoretical study of magnetic couplings in Fe_1-xM_x disordered bulk alloys and in Fe/M (001) superlattices (with M = V, Nb, Ta and Mo). The calculations were carried out using the charge and spin self-consistent Korringa-Kohn-Rostoker method combined with coherent-potential-approximation (KKR-CPA). For Fe _1-xV_x, site-decomposed magnetic moments were calculated according to two different models of completely and semi disordered alloys. For all the considered transition metals M, an antiferromagnetic (AF) coupling between the Fe and the M magnetic moments was determined. For small concentrations x (d-impurity in bcc Fe metal), the induced magnetic moment on the M atom is of -1.37μ_B for V and of about -0.6μ_B for M = Nb, Ta and Mo. The Fe magnetic moment was found to be 2.31μ _B, equal to that of pure bcc metal. When x increases up to 0.28, the Fe magnetic moment does not change noticeably, while the induced M magnetic moment decreases more dramatically, e.g. for M = V and Mo. Then, Fe ₅/M₁ and Fe₄/M₂ multilayered systems were considered. In all cases, an AF coupling between the Fe and M layers was derived, whose strength decreases from V to Mo atoms. The impact of the interface interdiffusion on the induced M and reduced Fe magnetic moments in Fe₅/M₁ and Fe₄/M₂ was also studied. The atom interdiffusion leads to an increase in the total and average iron magnetic moments, while the induced magnetic moment increases for M = V and remains constant for the other atoms.