This paper addresses the tensile response of Strain Hardening Ultra High Performance Fiber Reinforced Concretes (SH-UHPFRC) subjected to restrained autogenous shrinkage deformations under full and partial restraint conditions, right after casting and until one month. The development of autogenous shrinkage and corresponding eigenstresses under various degrees of restraint were studied for two types of mixes; Mix I with type I cement and silica fume, and Mix II with silica fume and 50% mass replacement of type I cement with limestone filler. The tests under 100% restraint conditions are the first of their kind on SH-UHPFRC and the results show that under these conditions, the material enters into the strain-hardening domain of the tensile response. The development of eigenstresses was much slower in the Mix II when compared to that of Mix I. The development of the dynamic elastic modulus and heat of hydration were also studied and put into perspective.