Neutron spin resonance mode is a common feature in different classes of magnetic superconductors; nonetheless, the microscopic origin of the mode is still unclear. In general, it is believed to arise from singlet-to-triplet excitations associated with electron Cooper pairs since all previously studied materials have singlet ground states. The situation for the heavy fermion superconductor UPt3 is quite different, as it is thought to be a triplet superconductor. We propose to search for a neutron spin-resonance in UPt3, which is particularly important and timely for the general understanding of magnetically mediated superconductors and the microscopic origin of the resonance. Since electron pairing in UPt3 may be a triplet, the discovery of a neutron resonance in this material would help to establish the origin of this collective mode.