Abstract: For a finite group G, a subgroup P of G is 2-minimal if B<P, where B=NG(S) for some Sylow 2-subgroup S of G, and B is contained in a unique maximal subgroup of P. For fields of odd characteristic, this paper contains a detailed and explicit description of all the 2-minimal subgroups of the finite general orthogonal groups, and certain of their subgroups.