Expressions for generalized inverses of a well-known bordered matrix are derived.These expressions find application in the solution of systems of linear equations obtained by using Lagrange multipliers to find a constrained minimum. In particular, they are used to obtain explicit representations for minimum variance linear unbiased estimates of estimable linear functions in the linear model with restricted parameters.1. Preliminary results. Several types of generalized inverse matrices have been introduced in the literature and studied primarily from the point of view of utility in solving systems of linear equations. Penrose [7], for example, showed that for any matrix X (we shall, however, consider only real matrices) there exists a unique generalized inverse. This matrix, which we shall call "the generalized inverse of X" (abbreviated to "the g-inverse") and denote by Xg, is defined by the relations (1) XXX-X, XXX -X , (XXg) '-XX , (XgX)'--XX.However, as Penrose himself pointed out, in order to write a solution to a set of consistent equations Xb y (boldface symbols represent vectors) in the form b Gy, we require only the first condition, viz. XGX X. We therefore define a one-condition generalized inverse (abbreviated to g-inverse) as any matrix X g' satisfying (2) xx'x x. Such a matrix is, of course, nonunique and for convenience we write G X to stand for "G is some g-inverse of X." The algebraic properties and statistical applications of this class of g-inverses have been studied in some detail by Bjer- Rao [9] and Rohde [13].In some statistical applications two further types of generalized inverses have been found useful. These further types are defined by the first two and the first three conditions of (1). We call the former a two-condition generalized inverse (gz-inverse; Xg2) and the latter a three-condition generalized inverse (g3-inverse; Xg3).In this paper, however, we shall be primarily concerned with g-inverses, various useful properties of which are summarized in the following lemma.