A polyester yarn having filaments with aperiodic varying shrinkage levels along their lengths, the filaments having within-filament and between-filament shrinkage C.V.'s of at least 10%. The yarn may be made by conventional melt spinning within a critical narrow range of spinning speeds wherein yarn shrinkage decreases rapidly with spinning speed. A greige fabric incorporating the yarn as filling is textured by shrinking the unrestrained fabric, then heating the fabric sufficiently to cause the yarn to elongate.