  We find the conditions for the existence of fermionic zero modes of the
fundamental representation in the background of a Kaluza-Klein (KK) monopole.
We show that while there is no zero mode without a real mass, a normalizable
zero mode appears once the real mass is sufficiently large. This provides an
elegant explanation for the known decoupling of KK monopole effects in
supersymmetric theories when a large real mass term is added. We also present
an application where the correct counting of KK zero modes plays an essential
role in understanding the non-perturbative effects determining the low-energy
dynamics.
