The problem of evaluating neutron yield from the (α, n) reaction in oxygen has been the subject of much experimental investigation for many years. However, the computational probe has not been extensive, basically due to lack of required data in the literature. Using a computer program, calculations were made to obtain the number of neutrons emitted when a particles from the 238Pu isotope interact with 18O. Neutron yield (n/α) is calculated specifically for each excited state of the recoil 21Ne isotope. The result is in good agreement with the experimental value.