Quantum structures are algebraic structures like quantum
logics (orthomodular posets and lattices), orthoalgebras,
effect algebras (D-posets) which model event structures of
quantum mechanics. The elements of orthomodular posets can
be represented by question observables having their spectrum
in $\{0,\,1\}$, so they are considered as two-valued
physical quantities. We show that if such a structure
possesses an order determining system of states (=
probability measures), it can be represented by a system of
fuzzy sets and conversely.
