The purpose of this paper is to compute the discriminant of an involution of the first kind on a finite dimensional division algebra over a field with a Henselian valuation of residual characteristic different from 2 in terms of residue information. The results depend on the kind of residue involution and on whether the division algebra is inertially split or not. For example, every involution on a division algebra of degree at least 4 which is not inertially split has discriminant 1. A nice application is the computation of the discriminant of the first given example in degree 4 of an indecomposable involution [\textit{S. A. Amitsur, L. H. Rowen, J.-P. Tignol}, Isr. J. Math. 33, 133-148 (1979; Zbl 0422.16010)]. Another application is that every involution on a totally ramified division algebra over a field with a Henselian valuation of residual characteristic different from 2 decomposes as a tensor product of involutions on quaternion algebras. In the final section, the authors investigate the set of discriminants of orthogonal involutions on division algebras over Henselian fields. They show that in a large number of cases this set is the group of square classes of reduced norms. This fact has now been proved for central simple algebras of degree at least 4 over arbitrary fields of characteristic different from 2 by \textit{R. Parimala, R. Sridharan} and \textit{V. Suresh} [Math. Ann. 297, 575-580 (1993; Zbl 0803.16013)].