The evolution of the structural and optical quality of molecular‐beam epitaxial (MBE) grown InAs/In0.52Al0.48As pseudomorphic quantum wells with increasing well thickness has been analyzed by transmission electron microscopy (TEM) and photoluminescence measurements. TEM was used to assess the commensurability of the samples as well as to confirm the build up of stress as the InAs layer is made thicker. Under our growth conditions, intense intrinsic photoluminescence is observed for InAs layers as thick as 30 Å. Beyond this thickness a deterioration of the photoluminescence characteristics occurs due to roughening of the interfaces rather than to relaxation of the InAs lattice.