The ${}^{18}\mathrm{O}(p,\alpha ){}^{15}\mathrm{N}$ reaction is of primary importance in several astrophysical scenarios, including fluorine nucleosynthesis inside asymptotic giant branch stars as well as oxygen and nitrogen isotopic ratios in meteorite grains. Thus the indirect measurement of the low energy region of the ${}^{18}\mathrm{O}(p,\alpha ){}^{15}\mathrm{N}$ reaction has been performed to reduce the nuclear uncertainty on theoretical predictions. In particular the strength of the 20 and 90 keV resonances has been deduced and the change in the reaction rate evaluated.