  The vacuum structure of the inert doublet model is analysed at the one-loop
level using the effective potential formalism, to verify the validity of
tree-level predictions for the properties of the global minimum. An inert
minimum (with massive fermions) and an inert-like minimum (with massless
fermions) can coexist at tree level. But the one-loop analysis reveals that the
allowed parameter space for the coexistence of more than one minimum is larger
than the tree-level expected one. It is also shown that for some choices of
parameters, the global minimum found at the one-loop level may be inert (or
inert-like), contrary to what the tree-level analysis indicates.
