Direct tension tests were conducted on plain concrete specimens in a stiff loading frame which allowed complete stress-deformation relations to be obtained. The suitability of the specimen shape and the testing apparatus was verified by finite-element analysis. The behaviours of notched and un-notched specimens with different water-cement ratios were examined and compared. Piecewise linear and exponential stress-deformation relations are proposed and interpreted physically. Relationships between fracture parameters fracture energy and brittleness indices) and basic strength properties are also presented.