The aim of this paper is to study the categorical relations between matroids, Goetschel-Voxman's fuzzy matroids and Shi's fuzzifying matroids. It is shown that the category of fuzzifying matroids is isomorphic to that of closed fuzzy matroids and the latter is concretely coreflective in the category of fuzzy matroids. The category of matroids can be embedded in that of fuzzifying matroids as a simultaneously concretely reflective and coreflective subcategory. 1. Introduction and Preliminaries Matroids were introduced by Whitney in 1935 as a generalization of both graphs and metric spaces. It is well known that matroids play an important role in math- ematics and especially in applied mathematics. Matroids are precisely the struc- tures for which the very simple and ecient greedy algorithm works (4, 10). In 1988, matroid theory was generalized to fuzzy fields by Goetschel and Voxman (7). Their approach to the fuzzification of matroids preserves many basic properties of crisp matroids. Fuzzy circuits, fuzzy rank functions and fuzzy closure operators are widely studied (5, 6, 7, 8), while none of the corresponding axioms has been established. In (11), based on the idea of a fuzzifying topology (12), Shi intro- duced a fuzzifying matroid and established a one-to-one correspondence between all fuzzifying matroids and all fuzzy rank functions. The aim of this paper is to study the relations among matroids, fuzzy matroids and fuzzifying matroids from a categorical viewpoint. The paper is organized as follows. In Section 2, we study the relations between the category of fuzzy matroids and that of closed fuzzy matroids and show that the category of closed fuzzy ma- troids CFM is a concretely coreflective full subcategory of the category of fuzzy matroids FM. In Section 3, the properties of fuzzifying matroids are studied. We show that FYM, the category of fuzzifying matroids, is isomorphic to CFM. In Section 4, we show that the category of matroids M can be embedded in FYM as a simultaneously concretely reflective and coreflective subcategory. In summary, we show that