A Transmission Electron Microscopy analysis of misfit stress based on the Stoney formula is proposed. It is applied to the GaInAs/(001)InP system to determine the residual stress for layers thicker than the critical thickness. The measured stress corresponds well to the value calculated using the elasticity theory and the nominal lattice mismatch: the structure is always nearly fully strained even for an epilayer two times larger than the critical thickness. Very few segments of misfit dislocation are observed indicating that the plastic relaxation is not active yet. A tentative explanation, based on the difficulty to create the core of a misfit dislocation, is explored.