A group theoretical generalization of the well-known Georgi–Jarlskog relations(m&mgr;/mr)=3(ms/mb)and(me/m&mgr;)=(1/3)2(md/ms)to neutrinos is found in the context ofSO(10).The new relations are(m&ngr;&mgr;/m&ngr;&tgr;)=16(mc/mt),and(m&ngr;e/m&ngr;&mgr;)=(1/16)2(mu/mc),which are consistent with present neutrino data, assuming the MSW solution for solar neutrinos. Inclusion of the LSND result with a constrained set of parameters is analyzed. With Abelian flavor symmetries dictating the form of the neutrino mass matrix we classify all consistent four and five parameter models that accommodate simultaneously the solar, atmospheric and LSND neutrino data. ©2000 American Institute of Physics.