Aromatic polyimides because of their structure process a unique property combination of outstanding thermal stability and radiation and solvent resistance. Their excellent mechanical and electrical properties make polyimides the materials of choice for a wide range of applications in the electronics industry. Polyimides have long been amorphous materials but recently, flexible hinge groups containing ether and ketone linkages have been incorporated into the polymer backbone . This results in increased flexibility and development of crystallinity. The introduction of crystallinity is an effective means of improving the melt processability, however, little work has been done to determine the effects of crystallinity on the insulating characteristics of polyimides. Here we report the dielectric behavior for the semicrystalline polyimide New-TPI , which is synthesized by Mitsui Toatsu Chemical Co. and film processed by Foster-Miller, Inc. We have used dielectric relaxation to study New-TPI, especially its behavior near Tg.