The shear-induced crystallization behavior of poly(butylene terephthalate) (PBT) has been investigated by in-situ small-angle X-ray scattering at temperatures of 198, 203, and 208 degreesC as well as by ex-situ atomic force microscopy. Increasing the shear rate and/or the shear strain enhances the crystallization kinetics. The acceleration of the crystallization saturates with increasing shear rate. A pronounced effect of the shear field on the Avrami exponent is observed at 198 degreesC but not at 203 and 208 degreesC, even though at the latter temperatures the relative reduction of the crystallization time induced by the shear is twice the value at 198 degreesC. Compared to some other polymers like isotactic polypropylene, the shear field leads only to a weak orientation of the PBT crystals. The Avrami exponent and the orientation induced by the shear field are interpreted on the basis of a microshish model. Microshish structures are due to the breaking up of shear-induced row nuclei at high temperatures. Finally, the shear field is found to lead to a decrease of the long period.