The internal structure of hydrated natural rubber was revealed by observation under the electron scanning microscope, using the cryofracturing technique. It showed that natural rubber in its hydrated state is made up of an agglomeration of rubber globules which retain their original shape and size and it is a diphasic medium during drying. The internal water transfer in a sheet of natural rubber during the falling rate drying period was studied. Experimental analysis of the development of water content profiles in the sheet substantiated a law of water transfer transfer using the water content gradient as the thermodynamic transfer force. The coefficient of transfer involved in the law was measured, and proved to be highly dependent on the water content.