The morphology of PA66/Kevlar-129 fiber specimens was investigated by means of polarized optical microscopy and scanning electron microscopy. The results indicated that, at crystallization temperatures ranging from 100 to 220degreesC, the transcrystallinity (TC) interphase always occurs. Both the TC interphase and spherulite morphology were present under various crystallization conditions. (C) 2004 Wiley Periodicals, Inc.