This paper examines the relations between law, economy and rationality in Fichte’s “The Closed Commercial State”. In order to do so, I will first focus on the relation that exists in such a work between the theory of contracts and the theory of value. I will argue that the peculiar theory of value exposed there is ultimately due to legal requirements derived from the Fichte’s notion of property. That notion obliges to ensure, not only that nobody suffers from necessity, but also that there is some equivalence in the benefits that the parties perform in an exchange. This leads Fichte to the problem —recurring in natural rights theories— of just price. The relations between Fichte's economic theory and the rationality attributed to juridical-economic agents will be examined below. Since this rationality coincides with the motivation that the political economy of its peers assigns to the agents, certain reasons for why Fichte rejected such economic theories are examined and proposed. It will be emphasized, finally, the disagreements that seem to exist between, on the one hand, Fichte's theory of law and economic theory and, on the other hand, the selfish rationality that constantly presupposes in the economic agents.