open gromov-witten invariants are essential ingredients of lagrangian-floer intersection theory, and they serve as quantum corrections in mirror symmetry from syz viewpoint. they are difficult to compute in general due to non-trivial obstructions in the moduli. in this talk, i will illustrate by examples how to compute open gromov-witten invariants of toric manifolds, by relating them to closed gromov-witten invariants which are better understood. this also gives an enumerative meaning of mirror maps. this is joint work with kwokwai chan, naichung leung and hsian-hua tseng.