Microencapsulation of active agents, for their controlled release, can be brought about by the method of interfacial polycondensation [1]. In this paper, the permeabilities of the polyurea microcapsules for encapsulated cyclohexane have been determined. It is shown that the product of the permeability and membrane thickness can be changed over at least an order of magnitude by changing the degree of crystallinity of the polymer forming the membranes.